The Future of Green Energy?

Switch on treeThe luxuries of our modern life are heavily dependent on having continuing access to a source of electricity. But power generation often requires consumption of limited resources like oil or coal, and generate high levels of pollution. Even “clean” energy sources like solar or hydroelectric power can significantly harm the environment.

Imagine a clean and green source of power that not only doesn’t harm the environment, but helps clean the air. Trees, for example, help reduce atmospheric carbon dioxide levels, and provide shade that makes use of electricity-hogging air conditioners less necessary. And trees and other plants, it turns out, can generate an electrical current that can be tapped.

The xylem tissue in vascular plants like trees transports water, ions and mineral nutrients as sap from the roots to the rest of the plant. There is a difference in voltage between xylem and the soil, which allows the potential for plants to generate an electrical current that could be tapped into.

Recently a team of Japanese scientists demonstrated that a battery could be created from 10 ordinary potted house plants connected in a circuit. They found their “green battery” could generate 3 volts and 3 microAmps of current. So far it has apparently only been used to power a blinking light.

Another research group lead by Brian Otis and Babak Parviz at the University of Washington has shown they can run a circuit entirely powered by Bigleaf maple trees. Their key to success seems to be the use of “nanocircuits”. These custom integrated circuits have lower power requirements than standard chips. Such low power circuits would have broad applications in wireless devices like smartphones and even biosensor contact lenses.

Current applications for tree-powered devices seem limited to monitoring of the environment and wildlife in remote areas where battery-powered devices would be impractical. Trees and other plants simply don’t generate enough power to run our appliances or smartphones.

But I think it’s possible that devices in the future using low-power chips might be able to run on plant power. And perhaps we could engineer trees to produce more tappable electricity. Perhaps we’ll end up living in real-life tree houses.

What do you think the future could bring?

More reading:

Ferris Jabr “The Shocking Truth: Trees are Electric” ScienceLine (2010)

Love CJ, Zhang S, Mershin A (2008) “Source of Sustained Voltage Difference between the Xylem of a Potted Ficus benjamina Tree and Its Soil.” PLoS ONE 3(8): e2963. doi:10.1371/journal.pone.0002963 (free article)

Yamaguchi, T. and Hashimoto, S. (2012), “A green battery by pot-plant power.” IEEJ Trans Elec Electron Eng, 7: 441–442. doi: 10.1002/tee.21754 (subscription required)

Himes C. et al (2010) “Ultralow voltage nanoelectronics powered directly, and solely, from a tree” IEEE Transactions on Nanotechnology 9(1): 2-5 doi:10.1109/TNANO.2009.2032293 (free pdf)

Image: Violation by hapal, on Flickr, licensed under Creative Commons.

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