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Microbial Cells

Discussion in 'Renewable Energy' started by Little Ghostman, May 1, 2018.

  1. Little Ghostman

    Little Ghostman Well-Known Member Most Helpful Member

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    I have a small microbial cell set up, its based on a demo from the journal of biological education. They use a bacteria that isnt so easy to source in the UK, so i decided to try a few others out.

    The target voltage for a 1ltr cell is roughly 0.8V, the last batch i used bakers yeast. Looking at the numbers from the logger it seems Yeast can put out 1.2V, now i confess this was a test of the set up and not really intended as a run, both electrodes are bog standard graphite. The load was by resistor and roughly 60mA, the figure wasnt picked for any particular reason.

    The cell ran for two weeks as i didnt get time to do much with it, but looking at the readings from the file, it seems the cell easily held its own over two weeks, but there is a sharp drop at the end, likely lack of food or polluted because i wasnt looking after it.

    Anyone else played with Microbial cells? I notice in one journal they got a new membrane material that is said to match a hydrogen cell, but really scant info at the moment, i could only get the abstract.
     
  2. Little Ghostman

    Little Ghostman Well-Known Member Most Helpful Member

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    One reason for the interest is a phenomenon seen on various electrodes in AD systems that give false readings due to microbes attaching to them. So i was looking at a solution to this and got interested in them. Not sure where it will lead but thinking about the size of some AD systems, there might be some merit in them. I am using a energy harvesting board (will link in a min) that runs a 32bit Arm Cortex 3 processor as the main data logger and control system for a small research AD system.

    I am about to try and power it from a microbial cell, before people jump on this take a look at the following videos. In my own cell i have used a different set of home made electrodes, but same principle. The harvesting kit is exactly the same as one of the ones i am using for this (wurth one), not that one of the energy sources runs from as little as 20mV to power the micro dev kit that comes with it (same dev board i am using to run the AD system).

    The vid on the actual microbe cell has an interesting bit at the end, they dont show you inside unfortunately, but an email to them got a reply saying look careful at end and you should see the cells inside. They wouldnt tell me how many cells is in the end container, but its got to be alot, having said that the room is about the same size as a normal mid size AD system. So it would be interesting to build a few simple cells and see what they can do.

    The other videos are on the energy kit webpage, not great info but shows what the various sources can do and shows the micro board being powered by them, one thing however.... They say the solar cell on the board works in low light, TBH the one in my kit is exactly the same and dosnt work as well, but the other sources do work really well.



    This one wasnt out when i got my kit! But man its some kit!! Maybe if i earn enough this summer i will get one, take a look at it as its really some bit of kit.
    https://www.mouser.co.uk/new/Wurth-Electronics/wurth-gleanergy-demo-kit/

    This is my one
    https://www.mouser.co.uk/new/Wurth-Electronics/wurth-energy-harvesting-to-go-kit/

    videos near page bottom. Anyone interested in long term field data loggers might find it useful, I will go dig out the datasheets for the chips, I know somewhere all the boards have full schematics, so making a battery free field logger shouldnt be too hard, the min voltage is 20mV, note a single small tub used as a microbe cell can produce 200mV+ easily, I have had over 1V from microbe cells but they are not really long term viable at the moment and need daily maintenance.
     
  3. Little Ghostman

    Little Ghostman Well-Known Member Most Helpful Member

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    Well interesting find video wise, i am tracking down the papers at the moment. I doubt many are interested in this (fair enough) but it opens some very interesting avenues for continuous flow reactors.
    Its a long thread and the focus isnt so much about the electric produced, but the figures given for sludge removal and especially heavy and precious metals recovery are pretty staggering. As a final free energy (almost) clean up stage, it would make a fantastic final chamber in a multi chamber system.

    I am tempted to empty a couple of my reactors and look into this, oddly he gets best results using material thats structurally similar to what i use, he uses very high temps to get it, i use drift wood and lower temps for the bio char, but the pore sizes look about the same. I am trying to find contact details for him. Anyway maybe one day in the future as this tech takes off, a google lander will find all this and it might be useful, i appreciate its a highly specialized area.

    I will also post some the details on the energy harvesting equipment from what was linear technology, anyone know what happened to all there app notes??



    Note when using these cells you get CO2 not methane, hence being a end stage digester unit. CO2 is ot the bogey man its made out to be, in AD systems it has many uses, even at the very end of the process it can be used to great effect if dissolved in water and fed hydroponically to plant roots of high value crops.

    Methane itself is from CO2 and H2 reactions, so the CO2 produced can be recycled back into the system if using a continuous cycle system. This is sort of the area i mess with in the lab, if it paid the bills its what i would do full time!

    Funny by the time i am 40-50 this will be common tech powering most homes...
     
    Last edited: May 4, 2018
  4. dave miyares

    Dave New Member

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  5. Little Ghostman

    Little Ghostman Well-Known Member Most Helpful Member

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    A rare beast! open access paper on MC's, i havnt read all of this one as i think its mainly a review, but might be of interest. Its certainly one way to desludge a AD in a continuous system.

    https://www.sciencedirect.com/science/article/pii/S1110016815000484?via=ihub

    EDIT
    Having read much of the above paper i would like to add some comments.

    Despite its date (2015) alot of the information and data tables are woefully outdated, it is mentioned within the paper that some of the tables have been taken from X or Y paper, on checking dates and the figures given these are outdated by a wide margin.

    Also the paper uses meter square often but dosnt always give the context, for example when talking about Anode surface area a square meter should in this context mean surface area of the entire substrate. So a square meter in this sense could be as small as 1cm when you consider the porosity of the material.

    In other areas they are in fact speaking about the plate area! So i am sorry its a bit confusing, the main problem is its open access, meaning we can share and post it without a publisher going for your throat.

    Better papers exist with much more up to date data, unfortunately only the abstract can be shared publicly. Modern abstracts (IMHO) give little information and miss the entire point of there existence. But apart from that :D its useful :D

    Oh one last grumble.....Platinum giving 6W per square meter does not take into account platinum poisons the substrate.
     
    Last edited: May 4, 2018
  6. large_ghostman

    large_ghostman Member

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    So what use are microbial cells? Well originally and to a greater extent even now, they were looked at as a way to generate electricity. But turns out they are most certainly not one trick ponies! Most research is still around energy production, most research is still in uni labs, the odd mad man shed and a few some scale companies.

    lets start with the obvious, electric production.
    On the face of it they dot produce much, but most people misread or dont make the mental leap from the figures to the potential. A good microbe cell is way more powerful and provide alot more energy than modern batteries! I will come back to that statement in a bit and back it up with the evidence. The thing is most cells are copies from old lab experiments, these used single anode plates to study the energy density. so you tube is full of microbe cells with a single Anode.

    What the people who make these videos fail to understand is, in a two chamber cell (anaerobic/aerobic) there is no reason you cant use one cathode and as many anode layers as you like. The caveat being you have to have at least 3-6mm of 'mud' between each plate, so best done in a tube with the Anodes laid horizontal. The limit then becomes how much oxygen you can shove into the cathode side, doing this can give some very big energy potentials.

    Downsides to this?

    You will literally eat more of the sludge than is practical to supply, although various current studies are trying to address this.

    part 2 soon
     
  7. large_ghostman

    large_ghostman Member

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    I have been challenged to build a remote controlled car powered by a microbial cell!! Car might be stretching the definition somewhat with what i have in mind lol, but i will post an outline of an idea. To add to the fun, i excepted this challenge purely because i have no idea if it can be done on a tiny scale! We are talking balsa wood or similar and a brushed motor of around 1V. Remote control will be a very basic self built unit.

    I will stick it in projects with some pics of the kind of thing i have in mind. The value in trying this however, is more in the discovery of actual energy densities in microbial cells, when your pushed to the limits space and weight wise. So useful data which ever way you look at it.
     
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