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michka:research:microbial_fuel_cells [2014-09-03 09:35] – michka | michka:research:microbial_fuel_cells [2014-10-03 12:52] – michka | ||
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- | ====Microbial Fuel Cells==== | + | ====Quick & Dirty Microbial Fuel Cells==== |
- | (see also [[: | + | 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. |
- | ====From Litterature==== | + | 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. |
- | ===Two containers + Air Pump Design=== | + | 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. |
- | [[http:// | + | So far, the peak power I measured was 0.5 mW [[michka:research: |
- | An airpump feeds clean water with oxygen for the reduction reaction: protons coming from sludge by the salt bridge, together with electrons coming from sludge by the wires, recombine with oxygen to make water. The airpump allows high current to be produced. | + | (see also [[:fuel_cell]] for futher info...) |
- | Performances: | + | ====Inspirations==== |
- | ===One container Design=== | + | I started this research by looking for existing quick & dirty designs online. I found two main categories of designs |
- | [[http:// | + | The **[[http:// |
- | ====Experiments==== | + | An airpump feeds clean water with oxygen for the reduction reaction: protons coming from sludge by the salt bridge, together with electrons coming from sludge by the wires, recombine with oxygen to make water. The airpump allows high current to be produced. |
- | ===One Container Design=== | + | Performances: |
- | {{ : | ||
- | * Wiring | + | The **[[http:// |
- | ==Results== | + | ===High-School Project Presentation=== |
- | * Peak voltage at 100mV, drops to 60, stable. | + | [[http:// |
- | * Voltage changes with oxygenation | + | |
- | ===One Container in Crate Design=== | + | ====Experiments==== |
- | | + | |
- | * Five times bigger cathode, made of wiring, and then replaced by a flattened aluminium can. | + | * [[michka: |
- | + | | |
- | ==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=== | + | |
- | + | ||
- | {{ :michka: | + | |
- | {{ :michka: | + | |
- | {{ : | + | |
- | + | ||
- | + | ||
- | | + | |
- | * 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=== | + | |
- | + | ||
- | {{ :michka: | + | |
- | + | ||
- | * 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=== | + | |
- | + | ||
- | * Maybe it needs a longer period to get started - eating up all the oxygen around the anode. | + | |
- | * Maybe our PEMs are not good. | + | |
====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 |