Back in 2005 when MagCap announced they were getting power from trees I tried a few experiments. I haven't returned to them since though. FWIW Here's a photo from back then along with the notes I made.
-Steve
http://rimstar.org<-- start of notes ----------------------------->
Jan 8, 2005
With 1 grounding rod hammered about 6" deep.
- I first nailed about a foot up the tree, into the wood. Voltage was
meaasured directly between the nail and the copper rod. Voltage was
around 1.004 volts but varied when I removed and reconnected the
probes and aligator clips from 1.004 to 0.94.
- I also measured across a 12ohm resistor and got significantly less voltage.
- I measured current in series with the 12ohm resistor and it was around
18microamps.
- I measured current in the 12ohm resistor and is was still around 18microamps.
- As a sanity test I measured with a nail that was just duct-taped to the
side of the bark. There must have been some capacitance because it quickly
dropped to single digit millivolts and kept dropping from there.
- I also measured with two other nails. One was higher up and showed around
the same voltage, 1.00volts. The other was in a crack in the bark so I did
not have to scrape the bark away first. It was also around 1.00volts.
Jan 9, 2005
- With 1 grounding rod, the results were, starting from top left nail
to bottom right nail:
49uA, 0.90V, 44uW
51uA, 0.79V, 40uW
34uA, 0.94V, 32uW
- With 2 grounding rods, the second one hammered about 12" deep:
57uA, 0.94V, 53uW
54uA, 0.82V, 44uW
37uA, 0.97V, 36uW
Note that the 2 grounding rods were connected at their top using two
wires with aligator clips (two were used to increase conductivity).
During the tests for 2 ground rods, the current fluctuated slowly,
sometimes going up and sometimes down. It was not random movement,
definately unidirectional. The voltage did likewise but possibly
more slowly. This may have been due to the two grounding rods being
at different potentials in the ground - though both were cut from
the same copper pipe. This type of fluctuation was not as prevelant
when using only one grounding rod.
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