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After watching a scene in the Matrix where they had humans hooked up to produce electricity I wandered if this could be done at any level with living plants in the soil?

All the examples online has the plant removed from the soil. Studies show the electrical current passing through a plant interrupts cellar function, but none of the studies where conducted with the plant in the ground and allowed time for the plant to recover.

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The medium be self sustaining where the plant never has to be tendered just hooked up in a field?

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closed as off-topic by sphennings, StephenG, CaM, RonJohn, L.Dutch Mar 16 '18 at 18:59

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "This question does not appear to be about worldbuilding, within the scope defined in the help center." – StephenG, RonJohn, L.Dutch
If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ That's one big potato... $\endgroup$ – JBH Mar 16 '18 at 17:51
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    $\begingroup$ What would be the point? The actual energy in a potato battery comes from the copper and zinc reacting. You can also use sea water, which is easier to come by than genetically modified potatoes. $\endgroup$ – Draconis Mar 16 '18 at 17:59
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    $\begingroup$ Ignoring why I found this article, it claims that if you boil the right kind of potato for the right length of time, you can actually pull energy from it more cheaply than you can an alkaline cell battery. $\endgroup$ – JBH Mar 16 '18 at 18:27
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    $\begingroup$ Yes, but that article is essentially nonsence. As Draconis says the energy comes from the zinc and the copper. $\endgroup$ – James K Mar 16 '18 at 18:34
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    $\begingroup$ @Muze, you asked this same question on Biology se (biology.stackexchange.com/questions/69376/…), where you accepted an answer and awarded a bounty. Why have you now cross-posted it here? $\endgroup$ – Dubukay Mar 16 '18 at 18:46
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You can....

A typical potato cell requires you to use energy to make some copper and some zinc. The metals store this energy and, if put in the right medium will give up the energy as electricity. Potato is a possible medium. So you then insert these metals into some potato.

The potato could be in the ground, but there is no benefit to the potato being there. The potato isn't providing any energy or electricity, that comes from the zinc and copper.

A typical potato cell has an emf of about 0.8 volts, and an internal resistance of several thousand ohms (lets say $2000\Omega$. If you want more power you can make a battery of lots of potatoes.

If you have 300 potatoes you could have a voltage of 240 volts. That is mains voltage in the UK. Nice! What happens if I want to run my laptop off of this.

Well my laptop apparently will draw up to 0.4 Amps of mains power at 240volts, so it has an effective resistance of $V/I=240/0.4 = 600\Omega$. But the potato battery has an internal resistance of $600000\Omega$. The voltage will be divided over my laptop and the internal resistance in the ratio 600:600000 = 1:1000, so of the 240Volts, my laptop only gets 0.24V, and a current of about 0.0004 A.

I can't power my laptop like that.

With sufficient potato cells wired in both series and in parallel it would be possible to get some useful power from them. But you will run out of copper and zinc pretty quickly, because most of the energy generated is used to overcome their internal resistance. The energy is used to gently warm the potatoes.

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To quote one of my favorite movies (The Hunt for Red October):

"Can you launch an ICBM horizontally?"

"Sure, why would you want to?"

Considering...

  • The time required to carefully remove soil to find all the potatoes, then insert electrodes, then recover the soil....

  • The electrodes being specifically designed to operate as expected inside the potato but not be subject to mineral or hydraulic decomposition1....

  • The wires connecting what would inevitably be miles of potatoes being hardened against weather and capable of very, very low resistance....

  • The collector (as simple as a battery) being of a type to harvest electricity at a very slow rate and yet distribute it quickly....

  • And nevermind the fact that you're probably going to do this all over again next spring....

The cost-to-benefit ratio for this idea is remarkably high.


1 You know... rust...

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    $\begingroup$ Definitely going to have to do it next spring... $\endgroup$ – RonJohn Mar 16 '18 at 18:33
  • $\begingroup$ not if you live where the ground does not freeze then it can grow year round and ad more probes as the potato grows.. $\endgroup$ – Muze the good Troll. Mar 16 '18 at 22:07
  • $\begingroup$ @Muze, I don't believe it's enough. I still believe it costs too much for too little benefit. Think of it this way: if one potato rots in the ground, the circuit is broken and you stop collecting electricity. You then have the privilege of hunting that one rotten potato down. $\endgroup$ – JBH Mar 17 '18 at 0:07
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It can be done, and it has been done, but to do it in a sustainable way, the yield is quite lower than say photovoltaics (from 200 to 300 times less), maintenance is low but still not zero, and setup costs are an issue.

The Matrix harvesting of humans also does not make any economic sense (it would have been much better to say that the Matrix is actually outsourcing some of its computations to some of the humans' neural circuitry - slow, but massively parallel).

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