Lime Jello, Yeast and Carbon Paper Fuel Cell




Can Jello Brand Instant Gelatin replace coal fired power plants? Probably not but it can be used to build a demonstration microbial fuel cell from common materials. This is a fun classroom or rainy day project, tie multiple cells together and use the power to light an LED. You'll probably need a joule thief as well. Output voltage and current are a function of cell volume and carbon electrode size.

Here's how it works, we're going to mix a little Jello brand Instant Gelatin with some Fleischmann's Active Yeast and a few drops of plant food. Once that solidifies we're going to cut out some fun Jello squares (yes, they still jiggle) and, using the carbon paper as electrodes, we're going to tap the energy produced by the yeast to create electricity.

This is an innovative form of the popular single cell microbial fuel cell or MFC. The gelatin serves a variety of useful purposes, including MFC container, fuel source and electrolyte. The yeast will feed primarily off of the sugar in the gelatin mix while the gelatin seals out ambient oxygen.

As you can see we started off with about 500 mV which ain't bad for some Jello and yeast...

Now let's get started!

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Step 1: Bill of Materials

Not much to this one.

The hardest item to find, believe it or not, was actual old fashioned carbon paper. I ended up ordering over the net since I couldn't find it in my local stores. Make sure you get real carbon paper since that is used for the carbon electrode and will significantly impact the performance of your MFC.

You'll need some instant gelatin. You want the kind with sugar in it (or that you add sugar to). I used Jello brand Instant Gelatin in lime flavor for reasons which will become obvious. Any gelatin should do, including unflavored gelatin with a cup or so of sugar dissolved in it.

You'll need some yeast. I used Fleischmann's Active Dry yeast for no particular reason other than it was there.

A candy thermometer or some other good way, including judgement, to keep from putting the yeast until the water has cooled down to 100 degrees or so.

A container, I used a square glass one that was handy. It should be convenient for cutting squares out of.

If you have some handy a little Instant-Gro or Shultz's plant food adds useful supplements to the medium.

Now that we have everything let's make some Jello...

Step 2: Preparing the Microbial Media

Nutrient media is a fancy name for gelatin, sugar, yeast and some nutrients.

Grab a bowl and pour the Jello mix into it.

Measure out two cups of water and place them off to the side with some ice cubes to cool it down.

Bring two cups of water to a strong boil. Make sure you get the full two cup measure of boiling water. Add this to the gelatin mix and stir for about two minutes. Make sure that all the contents are fully dissolved.

When the candy thermometer shows that the temperature has cooled to around 100 degrees add one packet of yeast and stir to dissolve. Stir for several minutes allowing the media to cool naturally. After about 5 minutes pour into the pan or mold you are using. Use the cold water to rinse out any yeast bits stuck to the side and pour into the mold. Mix well and place in refrigerator or freezer to set.

Step 3: Prepare the Electrodes

Once the jello has fully set ( a couple of hours ) we're ready to assemble our fuel cell.

First have we to make the carbon electrodes we will use to tap power from the MFC.

Cut a 2.5 inch strip from the bottom of the carbon paper, then cut 2.5 squares from that strip. This will form our electrodes.

Place one of pieces of carbon paper on a paper plate or other holder for your MFC. If you have an Easy Carbon Electrode you can place that on the anode, otherwise you can connect a lead from your MM directly to the anode.

Step 4: Charging and Operating

Okay now that we've got our two carbon paper electrodes cut out and the anode positioned We take our Jello out of the fridge and cut a square approximately 3 inches on a side.

Place that more or less carefully on top of the anode assembly. Now place the other piece of carbon paper on top of the Jello square. This is the cathode.

Attach one lead from your MM to the anode lead, attach the other to the cathode. As you can see in the intro picture I got an initial reading of approximately 500 mV which has subsequently dropped to about 280 mV on an open circuit.

You will notice that this ubiquitous green Jello just looks the part, don't it?

Plus, you know, it's really a green project...



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    104 Discussions


    1 year ago

    The experiment shows that yeast can produce electricity when consuming food. I have a question which I hope you can help, does providing electricity or electrons to yeast promote its growth?
    The reason I’m asking is there seems to be a flare up of yeast overgrowth when I tried earthing/grounding which essentially brings elecrons from the ground to our body which can help reduce inflammation and some health problems.



    3 years ago

    I really like this guide! But could the yeast be as effective in a standard 2-chamber setup?


    4 years ago on Step 2

    the yeast need nutrient to keep alive and "somehow" make energy right? so what if the nutrients from your nutrient media is already consumed? will you make another lime jello microbial fuel cell?


    9 years ago on Step 4

     is there any way we could connect several of this MFC's to produce energy that could light a small bulb?

    4 replies

    Reply 9 years ago on Step 4

    Absolutely, mkhabir ( ) has 30 LEDs running off an array he uses to light his room, as I recall it was approximately 10 gallons or so.

    The optimum configuration would be use an array of MFCs to feed a battery charger and use the recharged batteries to drive the light. The MFC generate power continuously at low levels, by using a rechargebable battery you can "compress" the stored power to a usable voltage.

    You can construct an easy test bed using one of those solar powered yard lights. Simply remove the top and clip the leads to the solar panel then attach the leads from your MFC array.

    Check out my for information on wiring the array.


    Reply 9 years ago on Step 4


    Newly, i also incorporated an solar panel to run the pumps and installed an Lithium Mobile battery charger to charge your phone from ALGAE?!


    10 years ago on Step 4

    Hey there...
    Thanks for your instructibles. I've only recently gotten into Bioelectricity and didn't realize harvesting it could be done so simply and easily...
    Besides the green jello looking the part I think that the lime flavoring (probably citric or ascorbic acid) served as your electrolyte. You didn't mention adding salt or any other electrolyte to the medium so did you luck out there or do the trace minerals which are there to feed the yeast serve a double purpose as ions? ... just wondering what conducts in the solid medium...
    BTW, here in the Philippines they still sell reams of carbon paper at office supply stores. I'm not sure what it costs now but maybe it would be cheaper than ordering from a specialty online supplier. Several reams through surface mail shouldn't cost that much if you plan to make a jello fuel cell battery to power your
    I thought about using CP for electrode material some years back but I thought the greasy binder would render it non conductive and wasn't going to buy a whole ream just to find out it was an insulator or had 1 megaohm resistance...haha
    In my electrochemistry work I use carbon cloth. Suppliers from China will give you a first time free sample of several square feet (and theirs is *Activated* carbon cloth...). I actually make standard carbonized fabric in the lab by heating denim or felt, etc. in the absence of oxygen...This gives a much greater surface area which will boost your Amps tremendously (and for an immobile fuel cell like your double tee junction pipe one, the CC's structural duradility should be adequate). Well, this is becoming an essay...more comments on other posts...Thanks again and Keep working for the Cause!

    5 replies

    Reply 10 years ago on Step 4

    I just lucked out. Now that you point it out I have no idea what the mechanism for ion transport is in this. Could be as simple as the coloring in the gelatin which would be extremely efficient at gathering stray bits. Can you provide a URL for the Chinese folks? Many of the research papers talk about carbon cloth but I haven't found a ready supplier. I can make biochar in my BBQ but hadn't considered cloth. Hmmm, could be an instructable in the works. I was very intrigued by the electron microscope carbon mesh. It seems a very convenient porous carbon electron that could be exploited easily. Plus the carbon is bonded directly to the electron collector grid, it doesn't get much better than that.


    Reply 10 years ago on Step 4

    As far as I know the ionic transport wouldn't be the food coloring. If I had to put money on it I'd say it was citric or ascorbic acid used to make the lime jello sour; however, the green dye used may be a facilitator which shuttles electrons from the microbes to the anode. Older microbial fuel cells used things like methyl blue and other compounds (used to stain histological samples in Biology so they were visible under the microscope) as facilitators. The newer ones just use microbes that don't need a facilitating agent (since most are very toxic and are considered pollutants). Since I don't think yeast cells (which you used) have the pili required to transport electrons w/o a facilitator you may just have stumbled upon a "green" (no pun intended) facilitator.
    My Organic Chemistry is pretty bad but I can say that if either of the two acids was serving as the electroluyte (and I can't imagine anything else in your cell that could have been) their ionic form in "jello solution" were your electrolyte ion transport molecules. More interesting to me is the green dye and if it is indeed a facilitator that is non-toxic. In any case, you can confirm if the lime flavor was the electrolyte by using jello without any flavoring (or any ionic compounds) or by using agar that is non-conductive as well. If your plain jello/agar cell gives almost no power you'll know it was an ingreduient in the lime jello. Try adding salt to both your lime cell and the plain one. the lime one may get a power boost and I'm sure the salt in the plain one will make it work (since it now has an electrolyte).
    I've just gone through a reformat so I don't have a URL for you but all the companies I ordered from do business on A search there or on Google for activated carbon cloth will yield many companies that will ship a free sample. I didn't pay for the shipping because I pulled out the "poor" card--as well as saying that I will be ordering huge amounts if their stuff lived up to their claimed specs. (Both my negotiation tactics are true, BTW...) But since you know how to make carbonized materials (wouldn't do it in your barbie though--chemicals and all in food...etc...) I wouldn't bother even paying for the shipping. They claim over 1000 square meters surface area per gram for the 3mm stuff I got--I just didn't see it act like that in the lab though; it also has bad conductivity unless compressed. Now that I know that my own carbon cloth works just as well and that carbon paper works too I'm shifting to those as electrodes.
    You mentioned electron microscope carbon mesh. I haven't come across that. From which instructable was it? If it's doped with electrocatalysts that would make it even better!



    Reply 9 years ago on Step 4

    Just a note from a self-taught baker... salt kills yeast!


    I have gotten reasonable results using carbon filters from aquarium pumps.

    You can probably verify the carbon paper with a conductivity test. There should be appromixately 0 resistance across the surface on the transfer side.

    Also the more holes you punch in the top, the greater the efficiency. This is a function of available oxygen and can be used in a bell jar to show power levels dropping as a candle burns the oxygen ( for instance ).

    3 replies

    We made our own carbon paper using plain white paper and bought some artist's carbon for drawing and just scribbled very thickly onto the paper. It worked! We got measurements of up to .22 mV. We are attempting it again today to see if we can get higher measurements.

    I still can't figure out what the mediator is in this project that is actually making it work. I was wrong about the fluoride in the water, that would actually make it work less if it had any effect at all. NaF prevents glycolysis. We tried this with plain gelatin with sugar added too, calculating the measurements of sugar in green gelatin, and an approximation of about 4g per tsp of sugar, so we added 20g of sugar to 1 cup of clear gelatin. We got some slight readings out of the plain gelatin, but it was much lower than the green. (.01 and .04 mV compared to .22 and .21 mV). So clearly something in the green is making it function better.

    The first time we did it, we also added too much yeast (thinking more yeast would produce more electricity), but it just got all puffy and didn't produce anything, probably processed all of the sugar before we even got to measuring it.

    That is an outstanding innovation. You could probably also use a #2 pencil. One gating factor is the amount of oxygen available at the surface electrode.

    You can briefly demonstrate this by blowing softly on the surface electrode, you should corresponding variances in current. It is not impossible that the current could also be improved by wetting the surface electrode with a saturated sugar solution.

    This will increase the availability of dissolved oxygen at the surface electrode and should increase current. The actual voltage is generated biologically by the yeast. This was first noticed in the 70's and subsequent research has varied. Visit for more information.

    The sugar in the jello acts both as food for the growing yeast colony as well as providing the necessary electron bridge between the electrodes. I have also noticed the difference in the gelatins, I suspect the dye+sugar is more conductive.

    I believe it would make an outstanding instructable if you were to do a well controlled test and measure the difference between the two media and document your results. That could also inspire other science fair projects.

    can i use carbon cloth instead of carbon paper? also, do you think this would suffice as a dumbed down version of a microbial fuel cell with containers as the anode and cathode, a salt bridge and the whole mile? SCIENCE FAIR IN 2 DAYS HELP PLEASE!!!!!!