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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.
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.
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.
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.
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.
A 2,308 V lemon battery.
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.
