Dirty Clean Power

Super Simple Soil Microbial Fuel Cell

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Single chamber Soil Microbial Fuel Cell, built using cheap/recycled everyday components. Power anybody can build.

These are prototype cells that I'm developing for the end goal of building a MFC battery of some kind. I have some distance to go yet, but I'm closing in.

This project is my attempt to perfect a simple low tech power producing soil microbial fuel cell.  I've been working on it and collecting data for several months now and will be sharing updates and design changes as well as attempting to develop it into a system for the production of useful clean power.

I intend to build at least 2 or 3 more of these in order to tune the design and components, it's a hurry up and wait kind of game. As each new cell stabilizes and is removed from incubation I will add another pair of meters to the board and a new cell will be constructed. I'll update the instructions as I make improvements and create a new project for the MFC battery when it becomes a thing.

  • 1 × Plastic or Glass Container To hold the cell, must not be metal
  • 4 × 100% copper dish scrubbers Other metals work, possibly better, but copper is cheap and easy.
  • 2 × Insulated Copper Wire 3ft
  • 1 × Soil The more nutrient rich, the better

  • No.11 found its forever home.

    williamolyolsona day ago 0 comments

     Lookin real comfy in there.

    Exactly 5 inches of head space.  Perfectly sized, ~2in of substrate to form the o2/proton membrane on top of the anode, and more than enough space to setup the cathode.

    No.10 was at 303mv 1.08ma at 8am.  It has since dropped to 302.  It was fairly warm last night so the cell temps are a full degree warmer this morning.  No.10 @ 17.5degC and no.9 @ 16.

  • No.10 Hits 300mv & New Anode for No.11.

    williamolyolson2 days ago 0 comments

    Been a very good day for cell no.10.

    Also, here's a first peak at the anode for cell no.11.  It's something completely different.

    That's a 1 liter water bottle in the middle.  It's about 9.5-10inches tall and likewise in diameter.  It should fit snug in a 5 gallon bucket.

    18 copper mesh scrubbers and some 12ga copper wire...  Plus an hour or two of twisting.  I like the result.  Looks a bit like a jellyfish.  I haven't weighed it yet, but it's a good chunk of copper.  More tomorrow!

  • No.10 bumping off 290mv this am.

    williamolyolson2 days ago 0 comments

    I can't yet be certain of it's going up or down at the moment, but we're still breaking new ground at this aprox. 16degC cell temp. range.  I think I'm going to give it another day or so to grow before I shut off the warm water circulation.  The reservoir temp.(measured outside of plastic bucket) is approximately 18degC.

    Either way it seems to be stable output and I'm fairly certain it's not done increasing.  I have yet to test the meter leads to see exactly how these two are comparing but I think it's safe to say no.10 is probably going to eclipse no.9.  Concerns of longevity will take some time still.

    I'm going to pick up some supplies today and hopefully start on cell no.11.  This one will be a bit more..More.

  • More output increases.

    williamolyolson3 days ago 0 comments

    Yesterday no.10 closed the night at 277mv 0.99ma 16.5degC.  This morning it was again at 277 0.99 yet at 15degC.  So, I can at least say the lower temps aren't negatively effecting performance.  In fact if the leads of both sets of meters had the same resistance(fairly sure they do not) then no.10 might actually be outperforming no.9.  I may swap meters around later and test that theory.

  • No.10 responded to temp drop.

    williamolyolson5 days ago 0 comments

    After lowering the incubation temp yesterday cell no.10s temp dropped from an average of about 20.5degC to about 19.  By 11:30pm last night it was generating 266mv 0.95ma.

    This morning @ 8:37am no.10 is at 268mv 0.96 cell temp 18.5degC.  I've again lowered the incubation temp. another 10degF, to its lowest setting.  One more day of slight warming and then we see what happens when nature takes over.

  • Turning the heat down.

    williamolyolson6 days ago 0 comments

    Well the last few days have been less than extraordinary.  Cell no.10 reached 263mv 0.94ma at 3pm on the 15th.  Since then the ambient temps have stabilized and so has the output, in the mid 250s.  I'm trying to get this cell to develop a kind of circadian rythem, so I guess it's time to wean it from the incubator and let nature take over.

    The fish tank heater in my water reservoir has been turned down about 10degF.  The current res. temp. is about 28degC.  I'll monitor the cell and report any significant developments, then tomorrow the heater will go down some more.  If I cannot get it to respond to temp changes reliably then I will have to call this cell a failure.  Though I will likely keep it around for a while and see what becomes of it. 

    One of the goals here is to develop a repeatable procedure for building these things in a timely manner.  So I guess as far as that goes I'm way off track already, lol.  I guess I should start hacking together cell no.11.

  • Another 10mv morning!

    williamolyolson10/14/2019 at 16:41 0 comments

    Cell no.10 is really starting to push.  At 9:09am it was reading 257mv 0.91ma 18.5degC, that's 10mv on yesterday's recorded high of 247mv 0.88ma 21degC.  It's presently bouncing off of 258&.92.

    No.9 continues to lead with a cell temp of 12.5degC, only loosely wrapped with insulation.  It has a mature microbe colony capable of exceeding 300mv in 20degC temps.  

    The next phase for no.10 will commence once the output peaks and has leveld out.  Then I will begin lowering the incubation temp a few degrees a day over the course of several days, ultimately removing it from the heat.  At which point it hopefully will have developed a microbe colony that behaves similarly to no.9 in that the output will be proportional to temp., and not inversely so as it still seems to be.

  • Continuing to rise.

    williamolyolson10/13/2019 at 18:28 0 comments

    Yesterday no.10s output fluctuated a bit, hitting 237mv mid-day then it was at 239mv by 10:30pm.  This morning at 9:14am it was at 245mv, 3mv over yesterday's high, and at 11am it was at 247mv 0.88ma.  We're slowly gaining day over day.  It's still a little erratic in its behavior(what conditions trigger output changes), but the output is otherwise very stable, so I'm guessing it just needs a little more time to stabilize and grow.  

    No.9 is rock solid as usual, and it just passed TWO months of continuous discharge, with ZERO signs of fatigue or fuel depletion.

  • Notable increase this morning.

    williamolyolson10/12/2019 at 20:44 0 comments

    10mv or more.  I'm guessing the cooler temps at night are more favorable for reproduction while the warmer are better for energy production..?  Who knows what's going on for sure, but gains are gains.  I completed the insulation and finally reached a 20degC cell temp.  Recycled bags do wonders.  I will build an enclosure at some point soon.

  • And just like that.

    williamolyolson10/11/2019 at 17:43 0 comments

    We have somewhat normal behavior.  Cell no.10 was reading 231mv 0.82ma @ 15.5degC around 8:45am today.  I was half expecting that something more dramatic would have been waiting this morning.  It's steadily rising with the ambient temps, right now bumping off of .83ma @ 232mv reading about 16.5degC.  We'll see if we can't coax a good daily rise out of it now.  It has to at least meet the output of no.9 in the next few days or it's just not worth fussing with it anymore.  For now though, this mess is still proving somewhat educational.

View all 24 project logs

  • 1
    Gather Components

    - A reasonable container, with lid, with enough vertical space to accommodate 5cm of soil space between the two electrodes, so minimum height will be the height of your electrodes + 5cm.  I use recycled plastic coffee cans, but any suitable plastic or glass container will do(no metal).

    - Some 100% copper dish scrubber pads and some insulated copper wire, about 2 arm lengths or so.  The wire pictured is certainly overkill.  The scrubbers I like to use unroll into a tube of woven copper, very easy to work with and  they are 2 for a dollar at the local dollar store.

    - Some soil mixed with some organic matter(compost, old coffee grounds, etc.), rough sifted so there aren't any large bits or stones.

    - A multi-meter, preferably two, to measure your success.

    - A pinch of patience and a fairly temperature stable place to allow your cell to incubate and polarize.

  • 2
    Assemble your electrodes!

    Unroll your scrubber pads and stretch and re-roll them into a larger ring shape.

    If your scrubbers do not unroll then you may have to simply pull them apart and use some copper wire to sculpt them into a suitable shape.

    I spliced two together and rolled a smaller ring with the other end of the tube so I ended up with two rings, one inside the other.

    Here are 2 complete electrodes.

  • 3
    Wire them up!

    Take your copper wires and strip them so they only have a foot or so of remaining shielding.  Now wrap those bare ends around each of the electrodes as many times as possible to ensure a good electrical connection at all times.  Feel free to weave it through a bit too.  The more contact your wire makes with the electrode the better. 

    Two electrodes ready for installation in container.

View all 5 instructions

Enjoy this project?



Stewart Lugosi wrote 10/14/2019 at 15:46 point

Really interesting project, I'm going to have to look into setting something like this up.

Is there a reason for horizontal anode\cathode rather than vertical?

  Are you sure? yes | no

williamolyolson wrote 10/14/2019 at 16:51 point

Thanks!  Yes, the anodic reaction is anaerobic(no oxygen), it is natural decomposition, which frees up electrons that travel through the wire where they ultimately pair with some oxygens and hydrogen protons at the cathode forming water.

Most fuel cells use expensive high tech membranes to keep the oxygen out of half of the cell, these use the soil substrate as the membrane.  The microbes in the 5cm of soil between the electrodes consume any/all the O2 before it can make it to the microbes living on the anode, forcing those electrons up the wire instead.  

So essentially the anode has to be a bit underground and the cathode has to be just touching it.  This could be achieved vertically, but I'm afraid the construction and materials would be a lot more complicated.

  Are you sure? yes | no

s0s wrote 10/11/2019 at 00:25 point

I love this. I love anything that helps Earth and the environment. I wish more people were like you. I just hope that humanity can stop climate change and start reversing it in time.

  Are you sure? yes | no

williamolyolson wrote 10/11/2019 at 05:03 point

Thanks, I wholeheartedly agree with you.

  Are you sure? yes | no

natevplas wrote 10/09/2019 at 16:20 point

Cool idea!  I realize this is just for fun, but do you think there's any feasible way to scale this up to a reasonably useful output?  I'm no electrician, but it would seem to me that you'd need at least 10 of these to power a single LED.

  Are you sure? yes | no

williamolyolson wrote 10/09/2019 at 16:45 point

Thanks!  It's a little more than just for fun, these are prototype cells that I'm building in order to develop a "battery" of microbial fuel cells.  There are a number of enhancements that can be made to the substrate and other aspects, for instance I've read in one paper that including blood-meal in the substrate can produce cells with voltages up to the 800mv range, significantly more millliamps as well.  My present concerns are mechanical/chemical stability of the electrodes and the longevity of stable energy production with simple components.  The primary goal though is to produce a cell with much more power output.  I'm presently on design no.10 all the cells that preceded no.9 we're drastically different in every way.  We will get there, I feel like it's more than feasible.

  Are you sure? yes | no

Tom Nardi wrote 10/06/2019 at 04:42 point

This is a dirty and disgusting project. I love it.

  Are you sure? yes | no

williamolyolson wrote 10/06/2019 at 17:22 point

Haha, thanks!

  Are you sure? yes | no

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