树木本身也能发电?

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If scientists have their way, we may someday be tapping maples—not for pancake fixin’s, but for power. Because researchers from the University of Washington in Seattle have found there’s enough electricity flowing in trees to run an electronic circuit.

If you’ve ever made a potato battery, you know that plant material can generate current. But the energy in trees is something else entirely. The potato experiment uses electrodes of two different metals to set up a charge difference that gets local electrons flowing.

But in the current study, researchers use electrodes made of the same material. Sticking one electrode into a tree and another in the soil, they found that big leaf maples generate a steady voltage of up to a few hundred millivolts. That’s way less than the volt-and-a-half provided by a standard AA battery. So the scientists designed a gadget so small, with parts just 130 nanometers in size, that it can run on tree power alone. Their results appear in the journal IEEE Transactions on Nanotechnology.

If you’re nuts for renewable energy, you probably can’t get much greener than a forest full of electrici-tree.

—Karen Hopkin