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====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_fuell_cells:Bruxelles2|during my experiments in Brussels]], which is still not sufficient.

(see also [[:fuel_cell]] for futher info...)

====From Litterature====

===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.

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.

Performances: 6V peaks, 200+ mA with airpump, 170 mA without.

===One container Design===

[[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.

===High-School Project Presentation===

[[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).

====Experiments====

   * [[michka:research:microbial_fuel_cells:Nantes1|Nantes1]]
   * [[michka:research:microbial_fuel_cells:Bruxelles2|Bruxelles2]]
   * [[michka:research:microbial_fuel_cells:Marseille3|Marseille3]]

====Design Improvements Ideas====

===Airpump===

   * Is the air pump giving more than what it pumps in terms of energy ?
   * Could we make a mechanical airpump coupled with a windmill ?
   * Could we improve the cathode design to remove the airpump ?

===Sludge===

   * 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 ?

===Electrodes===

   * 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