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michka:research:microbial_fuel_cells [2014-09-03 09:35] – michka | michka:research:microbial_fuel_cells [2014-10-03 12:47] – michka | ||
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- | ====Microbial Fuel Cells==== | + | ====Quick & Dirty Microbial Fuel Cells==== |
+ | |||
+ | A Microbial Fuel Cell (MFC) is a renewable electricity source based on soil microbial life. Anaerobic bacteria (living without oxygen) are produce electrons we can harness to feed our electrical circuits. It is a low-power energy source, working fine for lighting, or communication circuits sending data at low frequency. | ||
+ | |||
+ | MFCs are the object of advanced studies in many laboratories across the world. My objective is to design a MFC which can be build by anyone without specific prior knowledge out of abundant waste or bio- materials found in his/her close environment. The power is this quick & dirty MFC should be able to power a low-power LED. | ||
+ | |||
+ | I am currently playing with parameters: sample source, design geometry, electrode materials, nature of the proton exchange membrane (PEM), water source... To understand better the drivers of electrical power delivered by these Quick & Dirty MFCs. | ||
+ | |||
+ | So far, the peak power I measured was 0.5 mW [[michka: | ||
(see also [[: | (see also [[: | ||
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[[http:// | [[http:// | ||
- | ====Experiments==== | + | ===High-School Project Presentation=== |
- | ===One Container Design=== | + | [[http:// |
- | {{ : | + | ====Experiments==== |
- | + | ||
- | * Wiring as electrode. | + | |
- | + | ||
- | ==Results== | + | |
- | + | ||
- | * Peak voltage at 100mV, drops to 60, stable. | + | |
- | * Voltage changes with oxygenation - + 10 mV. | + | |
- | + | ||
- | ===One Container in Crate Design=== | + | |
- | + | ||
- | * Layed down the jar in a crate covered with a plastic bag and filled with water. | + | |
- | * Five times bigger cathode, made of wiring, and then replaced by a flattened aluminium can. | + | |
- | + | ||
- | ==Why ?== | + | |
- | + | ||
- | * Augemented cathode surface area & reduced water layer width for oxygen access. | + | |
- | + | ||
- | ==Results== | + | |
- | + | ||
- | * No improved voltage with bigger wiring cathode. | + | |
- | * Improved voltage (300 mV) with aluminium can cathode. | + | |
- | * When putting directly the multimeter cathode in water, we obtain 600 mV. | + | |
- | + | ||
- | ==Conclusion== | + | |
- | + | ||
- | * The geometry of the multimeter cathode may be better for voltage than the one made of wiring or aluminium can. However, surface area is necessary to obtain current. | + | |
- | + | ||
- | ===Crate Paper Design=== | + | |
- | + | ||
- | {{ : | + | |
- | {{ : | + | |
- | {{ : | + | |
- | + | ||
- | + | ||
- | * Flattened aluminium can as electrode. | + | |
- | * Thick paper sheet as PEM. | + | |
- | + | ||
- | ==Why?== | + | |
- | + | ||
- | * Reduced PEM width. | + | |
- | * Augmented electrode (both) surface area. | + | |
- | + | ||
- | ==Results== | + | |
- | + | ||
- | * Negative voltage when putting a rock on cathode to maintain it in water. | + | |
- | * No improved voltage by the new flat design. | + | |
- | * Still no current measurable, probably very low. | + | |
- | * The addition of coke drops (H+) at the cathode do not help current generation. | + | |
- | + | ||
- | ==Conclusion== | + | |
- | + | ||
- | * Is paper a good PEM ? | + | |
- | + | ||
- | ===Two Containers Design=== | + | |
- | + | ||
- | {{ : | + | |
- | + | ||
- | * Two bottles | + | |
- | * Saline bridge made of rope dipped in salt solution & wrapped in tape. | + | |
- | * Hard-drive metal box as electrode material. | + | |
- | + | ||
- | ==Results== | + | |
- | + | ||
- | * The addition of coke drops (H+) at the cathode do not help current generation. | + | |
- | + | ||
- | ===Other results=== | + | |
- | + | ||
- | * Two multimeter electrodes directly in water: about 30 mV. | + | |
- | * One mutimeter electrode on aluminium can dipped in water, one directly in water: about 30 mV. | + | |
- | * If water is not clean, voltage increases up to 100 mV. | + | |
- | * Two multimeter electrodes in the mud: 10-80 mV depending on location. | + | |
- | + | ||
- | ===Overall Conclusion=== | + | |
- | | + | |
- | | + | |
+ | * [[michka: | ||
====Design Improvements Ideas==== | ====Design Improvements Ideas==== | ||
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===Sludge=== | ===Sludge=== | ||
- | * Could we use compost tea as a sludge source ? Does it also work with usual soil ? | + | * Could we use compost tea as a sludge source ? |
+ | * See [[michka: | ||
+ | | ||
* How can we keep feeding the sludge, to make the fuel cell operation continuous ? | * How can we keep feeding the sludge, to make the fuel cell operation continuous ? | ||
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* Does the efficiency drops if we use flat electrodes from dead batteries ? | * Does the efficiency drops if we use flat electrodes from dead batteries ? | ||
+ | |||
+ | ====Other kinds of batteries==== | ||
+ | |||
+ | * Molten salt batteries | ||
+ | * Donald Sadaway, TED | ||
+ | * Zebra battery | ||
+ | * Rhubarb battery |