Introduction: Lime Jello, Yeast and Carbon Paper Fuel Cell

Picture of 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!

Step 1: Bill of Materials

Picture of 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

Picture of 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

Picture of 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

Picture of 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...


dlattori (author)2016-03-03

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

nobodyisintown (author)2015-07-04

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?

astral_mage (author)2013-10-05

sorry still no link.

meekah (author)2009-11-18

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

egbertfitzwilly (author)meekah2009-11-19

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.

that link u posted . it not there any more!!!

His link is in the next response in this list.

mhkabir (author)egbertfitzwilly2009-12-15


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

gizander (author)2009-08-04

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!

egbertfitzwilly (author)gizander2009-08-06

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.

dude u really need to go check out they will have it all.

gizander (author)egbertfitzwilly2009-08-07

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!


smash591 (author)gizander2010-01-14

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


egbertfitzwilly (author)gizander2009-08-07

I found the electron microscope stuff googling 'carbon mesh'

egbertfitzwilly (author)2012-04-18

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 ).

dstrater (author)egbertfitzwilly2012-04-29

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.

astral_mage (author)dstrater2013-09-28

try using char cloth. theres aplenty of instructable on that subject alone

egbertfitzwilly (author)dstrater2012-04-29

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!!!!!!

try using charcloth in place of yr carbon paper

I hope you got the science fair sorted out, I don't check my email on Instructables daily. Yes, carbon cloth would work instead of carbon paper. I wouldn't call it a dumbed down version of an MFC, I would call it an innovative design for a self consuming MFC that doesn't require external packaging.

ezhilabhi (author)2013-07-13

can any culture medium be used?

spiderfurby (author)2010-01-08

Would a carbon rod do - for example the carbon rods out of large "D"cells, or the carbon rod used for arc gouging? OR is there a Mcgyver way of making your own carbon paper? Maybe. I am thinking survivalist type ideas where u only have the minimum resources.

Yes a carbon rod, activated charcoal or raw charcoal can also be used.

In this instructable step 4 starts with: Now Macgyver

A DC motor brush from the local hardware store or power tool can also be used:

Thanks for your reply - I will investigate the alternatives - I am doing this for my son (10 years old) to give him an appreciation to the fact there is more ways of generating electricity than by coal or oil. The salt - idea is brilliant as well. I am from Victoria, Australia. We are in dire straits with regards to low rain fall and our water dams are disappearing quicker than we can replenish them. The government has come up with a brilliant idea of a desalination plant to turn sea water into drinkable water. But they are myopic with regards to the waste by product salt and are going to pump the concentrate back out to sea. This not very good for the sea life. But they instead my opinion they could of harnessed the salt energy to provide power for both the plant and possibly other townships. We have lots and lot of sun shine. By harnessing the sun and turning it in to a concentrated solar condenser they could crate salt baths and turn them into molten salt. Which in turn can then be used to provide heat to power steam generators - using again salt water. But no we rather pump it out to sea.  Why I have no idea.
We are also using  a method of under ground control burning of coal gas to produce energy for steam. Do you know how that works. It is an alternative to open cut mining. They use sea water to provide steam as well.

Actually it doesn't have to be that complex if supplies of aluminum feedstock are available. The concentrate can be electrolyzed into sodium hydroxide using power derived from microbial fuel cells based on the local municipal wastewater treatment facility. Using the sodium hydroxide as the electrolyte in an aluminum oxide fuel cell will produce clean cheap power far more reliably than solar. The aluminum can be recovered and reprocessed to create a sustainable energy cycle.

If you are in a position to submit a proposal I would be very interested in discussing this in more detail.

killbox (author)egbertfitzwilly2013-03-14

where do you get the energy to reprocess?

killbox (author)egbertfitzwilly2013-03-14

where do you get the energy to reprocess?

I saw an article which I have been searching in-vane for on the internet without success with regards to Norway providing Britain with large power station shipping tankers  that utilize aluminum and some other process to produce electricity. The tankers plug directly into the power grid and are capable of delivering power for 5 years. Once the Aluminum is oxidized it is sent back to Norway and is treated (some how to revitalize it) and also topped up with new aluminum then sent back. I just can not find the article any more.   I thought that this was innovative.

Its certainly possible. High capacity aluminum oxide batteries are available as commodity products. They are used in emergency power backup systems for the US PSTN among other things. There is no significant reason they could not be used ship board to drive electric motors.

The US DOE has selected the al-air battery as the primary candidate to replace the internal combustion engine for range, weight and compatability with the existing fuel infrastructure ( electrolyte replenishment ).

The configuration you outline may very well be cost, weight and range compatbile with a diesel electric system once a reason to invest in initial development such a system exists.

Johenix (author)spiderfurby2013-03-13

Geepers, why not suggest that the desalinization plant reject brine be fed to a plant extracting magnesium and bromine from sea water. Its already concentrated and then run the brine into a chlorine bleach plant.

 wait, for charcoal, you would insert one piece entirely into the Jell-O and one piece half into the Jell-O right?

I would put one piece under the jello and lay the other on top to get maximum surface area. I'm not sure how well the rods will work, I think you'll get power but I can't speak to its efficiency.

If you're talking about ordinary charcoal briquets I'd grind them up and use a layer of charcoal under the jello and a second layer on top.

 Aight, thanks, but i don't think that i understand what determines which electrode is positive and which one is negative. Is it that one is maybe exposed to air while the other isn't? 

That is correct. There is a detailed discussion of the exact mechanism on wikipedia:

I think that sprinkling fine charcoal powder on a sheet of paper saturated with salt water and then putting a heavy book on top would do it. (Though you'd have to wait for it to dry.)

dbell (author)2013-03-13

I was going to ask about how the heck this was polarized, but found your reply and link.

Since the air-exposed surface is an important active element, wouldn't a thinner layer of jello between much larger electrodes provide more energy, for the same volume? This would both increase the exposed surface area and reduce the bulk conduction path length.


suy2 (author)2011-11-30

what proportions did you use for this? i tried doing this but my gelatine gets all puffy as the yeast grows

egbertfitzwilly (author)suy22011-12-03

The gelatin is supposed to break down, it is consumed by the yeast colony.

suy2 (author)egbertfitzwilly2011-12-04

oh.. and uhm i tried making four units of gelatine battery which read 2V. i was trying to make a toy car function which only needs 1.5V to run but it won't function :|

egbertfitzwilly (author)suy22011-12-05

It is highly unlikely that you can power a vehicle of any sort with this. You simply can't get enough current. The best you can do is trickle charge the batteries that run the car.

Aaruni (author)2011-03-02

Is there any way thro which the electricity produced can be showed as a function of the sugar remaining in the cell or alcohol produced?

Maybe, using a glucose sensor or an alcohol detector..

Also, can u tell me how can i make 1 of these (Could not find them on d instructibles site)

cybergenius (author)2010-12-14

hey, i'm planning to make this for my science fair.......
can you please tell me how long this cell will last?????

BTW the instructable was gr8!!!!!!!!!!!!!!

Thank you for your kind words. The life of the cell is a function of multiple factors which can be measured and compared. I would recommend you use Knox unflavored gelatin ( in the same section of the market as Jello ) and add sugar in a controlled way.

The life of the cell is a function of food for the yeast and the mechanical integrity of the cell itself. Yeast is facultatively anaerobic and produces power because it is denied oxygen being literally smothered in Jello. As the Jello breaks down over a couple of days the yeast become exposed to oxygen. They revert to aerobic mode and begin converting the remaining sugar(s) to ethanol which is not a power producing reaction as far as anyone has determined.

The yeast are also limited by the supply of available food ( sugar ) in the gelatin, not all of which is accessible. Power drops as accessible sugar is consumed by an individual colonies within the cell body. These reach peak population and then begin to die due to lack of food and lack of room.

I'd say overall cell life probably ranges from a couple of days to a couple of weeks depending on the container, ambient conditions, amount of sugar and so on. These variables can be manipulated in controlled ways to produce exciting graphs and charts which are demonstrated by a series of cells in 5 gallon buckets that drive one or more LEDs to produce a visible power output.

nutsandbolts_64 (author)2010-11-07

I made 300 mV out of a 1x1cm dry cell (yes, one). Not the dry cell AA battery, as in a cell from a dry pile. Nice MFC by the way. I should probably make one for reserve.

wduck3 (author)2010-10-04

Could you use non-carbon electrodes, such as aluminum foil or a copper sheet?
BTW great instructable. I'm a fan :)

egbertfitzwilly (author)wduck32010-10-04

I believe you can. If I understand the original papers correctly the carbon electrodes were used to avoid confusion about the source of the power ( MFC versus a more traditional metal/electrolyte source ).

wduck3 (author)egbertfitzwilly2010-10-05

Thanks! I look forward to making one soon.

Unit042 (author)2010-04-02

(To the author if this Instructable) This is an amazingly simple and educational project here! The power output you achieved with mostly kitchen supplies is amazing.

From what I understand, the yeast eats the sugar and leaves electrons at the oxygen-lacking electrode, and the oxygen present electrode does its anode stuff.
There must be a way to contain the electrodes and 'electrolyte' so that Jello does not need to be used. Also, it would be advantageous to have this container shaped in such a fashion so as to encourage the addition of yeast-food; furthermore, a collection area for the dead yeast etc. gunk to pile up out of the way would go a long way toward MFC longevity.
Sugar powered LED's.... The combination of my two favorite substances...Mmmm....

Also, my younger brother has successfully made some wine with store-bought grape juice, sugar, and yeast. Oh, and time. About a month... or three? Anyway, do you think it would be possible to slap some electrodes on this and have it generate electricity as well as alcohol? But then again, there is oxygen present for the yeast to have...  if I have the anode deny the oxygen except through electrical reaction stuff, will the yeast's anaerobic consumption of glucose (sugar) then cease alcohol production?

Another side question: it is a commonly known fact that the yeast eventually produces enough alcohol to make the concentration of it lethal to themselves. I know that the alcohol is taken out by distilling (boiling alcohol out without boiling water out), but is it possible to remove the alcohol during the fermentation process without killing the yeast, so that yeast eats all the sugar present? Maybe hooking up a mild vacuum pump to lower the pressure to alcohol's evaporation point?

PS: Does it have to be "Fleischmann's Active Dry yeast " or will bread-machine yeast do?

egbertfitzwilly (author)Unit0422010-04-05

Thank you for your kind words and enthusiasm.

Yes, you're understanding of how it works is correct. Although there is still a great deal which is not understood about MFCs. Any yeast will do.

This is a novelty. Normally liquid medium is used ( wastewater is the most common ). MFCs can be constructed in one or two cell configurations, I've got instructables for both and there's a host of information available at

Careful with the homemade wine, other bacteria will also grow and may be dangerous. But yes, the same process can be used to generate electricity. If you used my two cell design ( requires some PVC pipe and a few other bits ) you can can do a great deal.

I have no idea how to remove the alcohol from the fluid.