

The Roots of Power: How Voltree is Tapping Tree Energy to Save Forests - rfreierman
http://www.xconomy.com/boston/2008/11/26/the-roots-of-power-how-voltree-is-tapping-tree-energy-to-save-forests/

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gjm11
Brief summary: If you stick an electrode into a tree and another into the
ground around it, the pH difference between the two media gives you a
difference in potential (~ 0.1V); you can draw a small current from this. (The
article doesn't indicate how much current. That seems kinda important.) It's
enough to power small sensors attached to the trees, which communicate
wirelessly with a base station. They hope to use this to monitor conditions in
forests so as to spot, or anticipate, or prevent, forest fires.

Despite the cutesy closing line calling Voltree a "green-energy company",
there is no prospect whatever of getting energy from trees to power household
appliances or anything like that. (Nor does anyone claim there is.)

Seems very neat, though.

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Retric
As I recall current is related to the size and shape of the electrodes,
potential is related to PH and the makeup of the electrodes. So you can't
really say what the current is without standardizing on a specific device.

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gjm11
I'd have thought that there'd be a maximum current you could draw without
making the potentials equalize. For small electrodes, the resistance between
the electrode and what it's connected to will be a limitation, but beyond a
certain point I'd expect it'll level off, the level basically being determined
by how much the tree's internal workings are doing to maintain its pH level.

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3pt14159
I was thinking the same thing. I'd like to set up a 3000 watt system in the
middle of the forest, right now it's looking like $35,000 for solar & misc
parts. If I could get it from trees though... I'm tempted to take an ohm meter
to work tomorrow.

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electromagnetic
I actually heard about this a long time ago, you can apparently make a crude
battery out of potted plants by connecting Plant A to the pot of Plant B and B
to the pot of C and so on. With a common ground, like a national park this
likely wouldn't work. However, connecting 500 trees in parallel rather than
series could provide a high current, which you could then run that high DC
current through an inverter and transformer and pump it up to whatever voltage
you need.

However, I'm not sure how practical connecting hundreds of trees in series
would be as you're going to get the problem of animals and what not. Unless
you wedged your electrodes in good, or found a way to allow the tree to grow
through them and hold them in place, you'd get trouble with squirrels pulling
them out trying to run on the wires and other crazy stuff.

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gruseom
Apart from the coolness of its subject, this article has a real cliffhanger of
a page turner. It's probably inadvertent, of course - but I dare you to resist
clicking "Next Page" :)

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josefresco
Ha, I noticed that as well, overall the story was well put together and
informative.

