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I'm thinking of an energy source where you could put organic life forms in and get out energy that could power something (edit: something that can be transported in a small space; where you can put plants in and get energy/electrons out anode and cathode, produces very little heat and last a long time).

I'll answer questions if you have any.

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  • $\begingroup$ Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. $\endgroup$
    – Community Bot
    Sep 10, 2022 at 13:01
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    $\begingroup$ Yes. You can metabolise them chemically to produce heat (like a compost bin), or make a fuel cell. Some plants will work better than others. $\endgroup$
    – user86462
    Sep 10, 2022 at 13:38
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    $\begingroup$ One common method is to feed the plants to animals that, in turn, do mechanical work. $\endgroup$
    – user535733
    Sep 10, 2022 at 14:54
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    $\begingroup$ Grow them. Sell them. Buy fuel. $\endgroup$ Sep 10, 2022 at 15:13
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    $\begingroup$ Glucose fuel cells are a thing, although they tend to be terrible for various reasons. $\endgroup$
    – TLW
    Sep 10, 2022 at 22:20

4 Answers 4

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Fermentation Heat:

Fermentation generates heat. The bigger the fermentation system, the more heat that you get out of it. In fact, soon fermentation systems will be so big that getting rid of the heat will be a major problem.

But if you're looking to capture energy, heat is your friend. While it isn't as powerful or sexy as fire, you can get electricity from a heat gradient using thermoelectric generators.

Horsepower:

The oldest way to get power from biomass. Feed it to an animal. Make the animal do work. Turn a wheel, and you can turn a generator. You may even be able to use your waste material from your fermentation system as feed for the animals to improve the efficiency of a combined system.

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  • $\begingroup$ @Exasperation I was certainly thinking that in answering, but didn't mention it since the question was about NOT burning. I had a vision of a drunken guy on a exercise bike cranking out electricity... ;) $\endgroup$
    – DWKraus
    Sep 19, 2022 at 15:41
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Microbial fuel cell?

https://en.wikipedia.org/wiki/Microbial_fuel_cell

Microbial fuel cell (MFC) is a type of bioelectrochemical fuel cell system[1] that generates electric current by diverting electrons produced from the microbial oxidation of reduced compounds (also known as fuel or electron donor) on the anode to oxidized compounds such as oxygen (also known as oxidizing agent or electron acceptor) on the cathode through an external electrical circuit. MFCs can be grouped into two general categories: mediated and unmediated. The first MFCs, demonstrated in the early 20th century, used a mediator: a chemical that transfers electrons from the bacteria in the cell to the anode. Unmediated MFCs emerged in the 1970s; in this type of MFC the bacteria typically have electrochemically active redox proteins such as cytochromes on their outer membrane that can transfer electrons directly to the anode.[2][3] In the 21st century MFCs have started to find commercial use in wastewater treatment

The microbes are alive and they can generate your lunch electricity for you. They do not burn. But here is the no such thing: a free lunch. Live things (heterotrophs like myself and the cat) need to eat something or (autotrophs like this vine which might be poison ivy) fix outside energy like sunlight. If an organism cannot take in the energy it needs, it starves and dies.

If you use a live microbial fuel cell you need to feed these microbes, ideally something you have but do not want, like poop. If you have a life form generating your electricity you need to give that life form food or energy that they can use, both to sustain themselves and to make the electricity.

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Yes, it could be possible to modify some plants so that you could take a small part of their energy harvesting process to generate fuels. For example, some fungi are able to tap into the plant process to get the energy they need.

However, the resulting energy will be small. Part of this is that you don't want to deprive the plant of resources it needs to keep growing. Another part is that plants are not all that efficient in capturing sunlight energy.

More energy can be gotten by growing perennial plants and harvesting the flowers, seeds, and stalks and converting them into energy.

Even more energy can be gotten by using more efficient solar collectors.

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A 2,308 V lemon battery.

enter image description here

The RSC team used 2,923 lemons to generate an astonishing 2,307.8 volts, which smashed the previous world record of 1,521 volts, and subsequently launching a battery-powered go-kart race run by the Blair Project in Manchester.

Source: Bath.ac.uk.

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    $\begingroup$ (Slightly off topic) I often see articles like this that imply that all of the "green" energy comes from the lemon. It neglects the energy required to make the anode and cathode which are destroyed in the process of generating electricity - not as "green" as it appears. $\endgroup$
    – andrew g
    Sep 11, 2022 at 12:25
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    $\begingroup$ @andrewg In fact, the lemon itself provides very little if any of the energy to a lemon battery. The energy all comes from the reaction of copper with zinc, and the lemon (specifically the citric acid in it) is merely acting as an electrolyte and maybe a bit of a catalyst. $\endgroup$
    – Hearth
    Sep 11, 2022 at 17:00

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