I'm designing an alien plant soecies that has evolved to produce electric shocks, as a way to keep insects away from it. My question is, how would it produce electricity in the first place? Also, could such an energy source be extracted? Note: I've read about the way electric eels produce electricity, I'm just wondering if the same method can be used by a plant. If not, in what ways could it produce electricity?
Very interesting question. The first thing that comes to mind is something along the lines of this. But in essence, this occurring naturally would be rather difficult and isn't really your plants creating the electricity so much as it is bacteria.
So what about an Enzymatic biofuel cell working off of the glucose your plant naturally produces in the Calvin Cycle? For this to work, your plant will need to produce a Glucose Oxidizing enzyme for the Anode and an O2 reducing enzyme for the cathode.
It wouldn't be difficult to imagine these being two different structures within your plant, perhaps quite small and close, with conductive structures near the surface. When an insect comes to feed, it completes the circuit with the conductive saliva in its mouth and gets shocked. A possible issue here would be rain short circuiting your plant, so you may want to make the conductive structures just below the surface the insect has to barely break the skin of your plant to get the shock.
If you really want to 'go-out-on-a-limb' (pun intended), you could have the plant generate natural capacitors using lipid structures and minerals pulled from the ground to produce charge storage devices allowing for greater potential differences (aka greater shocks). The issue here is that these will likely need to be grounded to properly work. But you plant can provide much of that using mineral pathways (likely separate and insulated from its vascular system) to the ground in which is grows. Whether this is necessary would depend on a lot of things, but insects probably wouldn't need large shocks in their mouths to be convinced to move on elsewhere.
And whether or not power could be extracted by an intelligent being, I see no reason why not. I would doubt that it is the most efficient way to generate energy from the sun, but this is based on current technology (solar panels).
Your plant has many long leaves that die away, dry, but keep hanging on the branches. Imagine ivy, but leaves are longer and dried up. When the wind blows, it causes leaves to rub together, and this builds static electricity. If branches are not conductive (very dry, too), leaves would retain that static charge for long time.
Rain would render that plant safe for some time, and leaves should not have pointy ends to keep the charge better.
Firstly the would need to develop something like a nervous system. An arrange of cells like a cable or chain that transfer energy from someplace to somewhere.
Let's say it can generate energy from the heat of the sun and let's call it photosynthesis! In the middle of the process the energy is stored in molecules, but them the organisms gets enough of it and the energy needs to go somewhere else. This process, in a oversimplified way, just transfer energy from the radiation of the sun to move electrons through molecules.
If this process also occurs in the chain cells until it arrives in the roots where the energy if finally stored for good, any disturbance of the cells membrane could cause an override and potentially create a discharge of electricity.
Disclaimer: If you want pinpoint accurate biology and reality check, take this answer with a grain of salt. You could mix some ions canals for a more accurate scientific process, but you would basically get what you already have, the eel situation.