Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revision Previous revision
Next revision
Previous revision
michka:research:microbial_fuel_cells [2014-07-11 10:38] michkamichka:research:microbial_fuel_cells [2018-04-26 12:44] (current) – [Experiments] michka
Line 1: Line 1:
-====Microbial Fuel Cells====+====Quick & Dirty Microbial Fuel Cells====
  
-(see also [[:fuel_cell]] for futher info...)+A Microbial Fuel Cell (MFC) is a renewable electricity source based on soil microbial lifeAnaerobic bacteria (living without oxygen) are produce electrons we can harness to feed our electrical circuitsIt 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://www.instructables.com/id/DIY-Microbial-Fuel-Cell-easy/|This design]] is made of two containers, bridged together with salt bridge (rope dipped in saturated salted water, wrapped in insulating tape), one with pond sludge, another with clear water.+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 to power LED.
  
-An airpump feeds clean water with oxygen for the reduction reactionprotons coming from sludge by the salt bridge, together with electrons coming from sludge by the wires, recombine with oxygen to make waterThe airpump allows high current to be produced.+(see also [[:fuel_cell]] for futher info...)
  
-Performances: 6V peaks, 200+ mA with airpump, 170 mA without.+These preliminary experiments layed the ground for the "Power of the mud" project created with robotic artist [[http://www.zprod.org/zwp/|Paul Granjon]].
  
-===One container Design===+====Litterature====
  
-[[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.+I started this research by looking for existing quick & dirty designs onlineI found two main categories of designs
  
-====Experiments====+The **[[http://www.instructables.com/id/DIY-Microbial-Fuel-Cell-easy/|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.
  
-===One Container Design===+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.
  
-   * Wiring as electrode.+Performances: 6V peaks, 200+ mV with airpump, 170 mV without.
  
-==Results== 
  
-   Peak voltage at 100mVdrops to 60stable. +The **[[http://www.treehugger.com/slideshows/gadgets/make-microbial-fuel-cell/page/1/#slide-top| one-container design]]** is made from one container, sludge at the bottomsmart gel proton exchanger on top of itand clean water on the very topNo air pump, but lower performances. Something like charcoal is used as an electrode material.
-   * Voltage changes with oxygenation - + 10 mV.+
  
-===One Container in Crate Design=== 
  
-   * Layed down the jar in crate covered with a plastic bag and filled with water. +I also found [[http://prezi.com/aw1kjprkgphz/tpe-comment-augmenter-et-utiliser-la-production-denergie-a-partir-dexcrement-de-cheval/|presentation]] made by a group of students on low-tech horse-crap-based MFCswith actual power figures in it (about 100mW for 120g of horsecrap). Interesting aspect of their designs: they use a small sponge covered with rocks as proton exchange membrane.
-   * Five times bigger cathode, made of wiringand then replaced by flattened aluminium can.+
  
-==Why ?==+====Experiments====
  
-   Augemented cathode surface area & reduced water layer width for oxygen access.+   [[michka:research:microbial_fuel_cells:Nantes1|Nantes1]] 
 +   * [[michka:research:microbial_fuel_cells:Bruxelles2|Bruxelles2]] 
 +   * [[michka:research:microbial_fuel_cells:Marseille3|Marseille3]] 
 +   * [[http://fablabo.net/wiki/Pile_microbienne|Nantes4 (in French)]] 
 +   * [[michka:research:microbial_fuel_cells:Cardiff5|Cardiff5]] 
 +   * [[michka:research:microbial_fuel_cells:Cardiff5|Cardiff6]] 
 +   * [[michka:research:microbial_fuel_cells:Cardiff5|Brussels7]] 
 +   * [[michka:research:microbial_fuel_cells:Cardiff5|Cardiff8]]
  
-==Results==+====Design Improvements Ideas====
  
-   * No improved voltage with bigger wiring cathode. +===Electrical integration===
-   * Improved voltage (300 mV) with aluminium can cathode. +
-   * When putting directly the multimeter cathode in water, we obtain 600 mV.+
  
-==Conclusion==+* Try to integrate the MFC with a [[https://www.youtube.com/watch?v=9t4DumnpFLA|Joule Thief]] and supercapacitors to see if we can obtain a functional system for intermittent power generation.
  
-   * 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.+===Sludge===
  
-===Crate Paper Design===+   * Could we use compost tea as a sludge source ? 
 +     * See [[michka:research:microbial_fuel_cells:Bruxelles2|here]] for the quite good performances obtained with compost tea. 
 +   * Does it also work with usual soil ? 
 +     * A brief experiment in [[michka:research:microbial_fuel_cells:Marseille3|Marseille]] gave bad signs. The battery was flat after two hours on measurements. However, longer-term experiments should be performed to let time to the anaerobic bacterial consortium to develop. 
 +   * How can we keep feeding the sludge, to make the fuel cell operation continuous ? 
 +     * Reverse the design, to allow waste to be piled up on top of a nutrients pile for the MFC, and be slowly degraded.
  
-   * Flattened aluminium can as electrode. +===Electrodes===
-   * Thick paper sheet as PEM.+
  
-==Why?== +   Does the efficiency drops if we use flat electrodes from dead batteries 
- +     Actuallythe [[michka:research:microbial_fuel_cells:bruxelles2|best power value measured so far]] was obtained with copper electrodes from dead batteries (scraps from the [[michka:research:supercapacitors|supercapacitors research workshop]]).
-   * 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. +
- +
-==Conclusion== +
- +
-   * Is paper a good PEM +
- +
-===Two Containers Design=== +
- +
-Hard-drive metal box as electrode material. +
- +
-===Other results=== +
- +
-   Two multimeter electrodes directly in water: about 30 mV. +
-   * One mutimeter electrode on aluminium can dipped in waterone directly in waterabout 30 mV. +
-     * If water is not clean, voltage increases up to 100 mV. +
-   * Two multimeter electrodes in the mud10-80 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====+
  
 ===Airpump=== ===Airpump===
  
-   * Is the air pump giving more than what it pumps in terms of energy ?+   * Is the electric air pump giving more energy than what it pumps ? 
 +     * Most probably not.
    * Could we make a mechanical airpump coupled with a windmill ?    * Could we make a mechanical airpump coupled with a windmill ?
 +     * Probably. But how useful would this be ? We should maybe focus on gathering the energy of the windmill.
    * Could we improve the cathode design to remove the airpump ?    * Could we improve the cathode design to remove the airpump ?
  
-===Sludge===+====Related====
  
-   Could we use compost tea as a sludge source ? Does it also work with usual soil ? +   Other battery designs: 
-   How can we keep feeding the sludge, to make the fuel cell operation continuous ? +     Molten salt batteries 
- +       * [[http://www.ted.com/talks/donald_sadoway_the_missing_link_to_renewable_energy?language=fr|Donald Sadaway, TED]] 
-===Electrodes==+       * Zebra battery 
- +   Rhubarb battery
-   Does the efficiency drops if we use flat electrodes from dead batteries ?+
  • michka/research/microbial_fuel_cells.1405075089.txt.gz
  • Last modified: 2014-07-11 10:38
  • by michka