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michka:research:microbial_fuel_cells [2014-09-03 09:35] – michkamichka:research:microbial_fuel_cells [2014-10-03 12:50] – 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:research:microbial_fuel_cells:Bruxelles2|during my experiments in Brussels]], which is still not sufficient.
  
 (see also [[:fuel_cell]] for futher info...) (see also [[:fuel_cell]] for futher info...)
  
-====From Litterature====+====Inspirations==== 
 + 
 +I started this research by looking for existing quick & dirty designs online. I found two main categories of designs
  
 ===Two containers + Air Pump Design=== ===Two containers + Air Pump Design===
  
-[[http://www.instructables.com/id/DIY-Microbial-Fuel-Cell-easy/|This design]] is made of two containers, bridged together with a salt bridge (rope dipped in saturated salted water, wrapped in insulating tape), one with pond sludge, another with clear water.+[[http://www.instructables.com/id/DIY-Microbial-Fuel-Cell-easy/|This **two-container + air pump** design]] is made of two containers, bridged together with a salt bridge (rope dipped in saturated salted water, wrapped in insulating tape), one with pond sludge, another with clear water.
  
 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. 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.
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 [[http://www.treehugger.com/slideshows/gadgets/make-microbial-fuel-cell/page/1/#slide-top|This design]] is made from one container, sludge at the bottom, smart gel proton exchanger on top of it, and clean water on the very top. No air pump, but lower performances. Something like charcoal is used as an electrode material. [[http://www.treehugger.com/slideshows/gadgets/make-microbial-fuel-cell/page/1/#slide-top|This design]] is made from one container, sludge at the bottom, smart gel proton exchanger on top of it, and clean water on the very top. No air pump, but lower performances. Something like charcoal is used as an electrode material.
  
-====Experiments====+===High-School Project Presentation===
  
-===One Container Design===+[[http://prezi.com/aw1kjprkgphz/tpe-comment-augmenter-et-utiliser-la-production-denergie-a-partir-dexcrement-de-cheval/|This is]] a presentation made by a group of students on low-tech horse-crap-based MFCs, with actual power figures in it (about 100mW for 120g of horsecrap).
  
-{{ :michka:research:img_5901.jpg?300 |}} +====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=== +
- +
-{{ :michka:research:img_5905.jpg?300 |}} +
-{{ :michka:research:img_5906.jpg?300 |}} +
-{{ :michka:research:img_5946.jpg?300 |}} +
- +
- +
-   * 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=== +
- +
-{{ :michka:research:img_5948.jpg?300 |}} +
- +
-   * 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. +   * [[michka:research:microbial_fuel_cells:Nantes1|Nantes1]] 
-   * Maybe our PEMs are not good.+   * [[michka:research:microbial_fuel_cells:Bruxelles2|Bruxelles2]] 
 +   * [[michka:research:microbial_fuel_cells:Marseille3|Marseille3]]
  
 ====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:research:microbial_fuel_cells:Bruxelles2|here]] for performances obtained with compost tea. 
 +   * Does it also work with usual soil ?
    * 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
  • michka/research/microbial_fuel_cells.txt
  • Last modified: 2018-04-26 12:44
  • by michka