Harvesting energy may eventually move away from the "Shake it, shake it real good" style of a giant windmill to the gentle sway of an artificial leafless tree pulling energy from movement.
Sounds crazy, but it's true. Ohio State University is doing ongoing research to learn whether technology that looks like fake trees can stir up consistent and renewable power when moved by wind -- or by a tall building's sway, bridge traffic or seismic activity.
In a recent study report, the Ohio State researchers said that they had turned up something new. They've shown that structures made somewhat in the shape of trees, constructed of electromechanical materials, can turn random forces (think winds, or footfalls on a bridge) into vibrations that move with strength through the structure to generate electricity.
On a small scale in particular, this technology may prove valuable. For instance, the system could potentially help save the day in situations when solar or other renewable energy sources will not work, project leader Ryan Harne at Ohio State, said.
But if you're picturing a mighty oak or a tall gingko, think again: These trees would be more like a trunk with a few branches and no leaves.
Early uses for this pole-tree would likely involve maintaining power to sensors for civil infrastructure -- basically, keeping up the health and structural integrity of bridges and buildings. The tiny trees might be a source of voltage to a sensor on a bridge underside, or on a girder within a multi-story building.
"Buildings sway ever so slightly in the wind, bridges oscillate when we drive on them and car suspensions absorb bumps in the road," Harne said. "In fact, 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."
Turning the vibrations into energy would allow monitoring systems to be powered by the vibrations that they are monitoring. At this point, structural sensors require batteries or being plugged into power lines. Both of those solutions are costly and can be difficult to maintain when sensors are located in remote spots.
Until now, scientists had not made an all-out effort to try using a tree shape constructed of electromechanical materials to bring in vibrations as energy. It was thought that generating consistent movement from random natural forces such as seismology and others wouldn't work well.
But the researchers on this project used mathematical modeling to find that maintaining vibrations in this way might indeed be possible. They realized they'd be able to use something called "internal resonance" to grab and store the energy. Already, certain mechanical systems can dissipate their internal energies in this way.
Then Harne and colleagues tested their model on two different structures, and eventually were able to produce consistent levels of voltage.
The findings were published in the Journal of Sound and Vibration.
