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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!
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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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...
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...
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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 ).
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.
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 microbialfuelcell.org 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.
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)
can you please tell me how long this cell will last?????
BTW the instructable was gr8!!!!!!!!!!!!!!
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.
BTW great instructable. I'm a fan :)
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?
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 microbialfuelcell.org.
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 www.instructables.com/id/Make-a-Microbial-Fuel-Cell-MFC-Part-II/ can do a great deal.
I have no idea how to remove the alcohol from the fluid.
Take a dead carbon zinc battery apart and take out the carbon rod and save the zinc case.
Fill a jar with water and add salt until its slightly white.
Hook wires up, one to the carbon rod, one to the zinc case.
Dip the electrodes in the jar.
To recharge, connect to 6-12v ! and it will restore its state to 1V.
Do you have a voltmeter? At .5V and a couple of hundred mA I'm not sure a joule thief will help, sure it will amplify the voltage but it isn't going to turn .5V into 50V
The yeast will breed up, the size of the initial colony probably affects the initial voltage but at some point the yeast colony will stabilize and begin to decline. I suspect that more initial yeast will shorten the life of the cell due to increased food consumption, I'm not sure if would significantly affect overall power output.
The amount of sugar affects how long that cycle lasts. The more sugar, the more yeast, the more yeast the more power at peak.
For making Agar nutrient media buy some vegetarian gelatin (this is not an animal rights thing, it's just that real gelatin is not quite as good for yeast - despite the fact that the Bacto-Peptone is made from roughly the same things).
Use the vegetarian gelatine in the following recipes:
A better broth for yeast is the following
Yeast Broth
Yeast extract 5g (Marmite works - if it calls itself yeast extract and you can find out that it is "autolysed yeast extract" - then it is a substititute).
Mix ingredients well. Autoclave for twenty minutes (alternatively, get a pressure cooker, place the mixture in a strong glass casserole dish and pressure cook for twenty minutes). This nutrient mixture can then be used to add into Jelly as a nutrient.Bacto-peptone 10g (This is usually produced from pulped and boiled animal bones. Realistically, you could substitute well strained, very reduced, bone stock for the distilled water).
Glucose 10g (you can buy from a brewing supply shop)
Distilled water 500ml
For example. Make yeast broth, Add 10g vegetarian gelatin. Autoclave for 20 minutes.
There are literally hundreds of recipes for media and this broth is just a simple one. The other substitute for Jello is cargeenan, which is - again - produced from seaweed.
Part of the choice of nutrient broth depends on the type of yeast chosen. Bottom brewing yeast is significantly different from top brewing yeast in what it likes.
The idea of yeast making electricity is kinda neat, but it works only until the yeast has enough food to be alive and the whole thing is spoiled quite fast I'm afraid.....
I have seen references to various brewers (I think it was Bud but am not prepared to say why...) evaluating the technology as a mechanism for tapping into their existing resources.
This particular application is clearly a novelty, its actually an experiment with using carbon paper electrodes with the lime jello popping up as a way to hold the electrodes.
The concept is quite interesting for some applications such as anaerobic digesters where suspension of the material in a uniform way may produce a higher wattage and so on and so forth....
Plus how often does one get to make a gizmo out of Lime Jello?
The idea is neat BTW and it reminds me of the "lemon battery" princible, though here the gelatine with the yeast seems to play a double role: an electrolyte and an electrode.
Dr. Bruce Logan at Penn State is, I think, the leading researcher in the field and his page contains most, if not all, of his publications. Dr. Hui at Oregon State is also doing some very interesting work. There's two pieces of carbon paper in the assembly, one on the bottom (concealed by the Jello) and on on top. These act as electrodes, the question of what, exactly, in the Jello mixture is acting as an electrolyte has been kicked around. I think its the sugar since in a classic salt bridge ( salt in agar ) the salt serves as the electroylte.
:D
Worth a test and let me know how it works out.
If you have a voltmeter I would be very interested in the power curve you get for your experiments. Just measure the voltage and current several times a day (whenever its convenient) and note the times and output over a week or so (or until the voltage drops below anything at all useful).
If you done a couple please publish an instructable and share your experiments. Even if "pure" scientific method isn't followed the results can be very informative and useful to others. Plus it will make you feel smarter, trust me....:-)
I have no good theory about how one might measure the yeast population, that's the really interesting bit. A theoretical population can be guesstimated but doesn't really reflect the population growth curve.