November MudWatt Feature!

This month we've got a feature on Ana. She just finished up an experiment with SEVEN(!) MudWatts for a school Science Fair Project. We sat down for a Q&A with her to learn a little more about her and her project!


Can you give us an overview of your experiment? (i.e. how many mudwatts were you running, where did the mud come from, how long did you run the experiment, what was your hypothesis, what were the variables and constants, and what was your conclusion)

I ran 7 Mudwatts for 30 days.  I obtained soil from under a blackberry bush at a local farm (agricultural), from my parents' garden (garden), from the area they pen te cows at a local farm (cow enclosure), and, from a nature park, soil was taken from under a paw paw tree (forest), from the dirt made from a decomposing tree (decomposing tree), from the stream that runs through the park (stream), and from a frog pond (frog pond).  

My question was what type of soil can best power microbial fuel cells, which soil type makes the most power, and which soil type produces the most consistent power.  My goal in this project was to find out if microbes can make power that could benefit our communities, and maybe even help save the Earth as a source of alternative energy.  We need stop or slow down global warming and climate change.

My hypothesis was that if I compared seven different types of soil (agricultural, garden, frog pond, stream, forest, cow enclosure, decomposing tree) in the same environment and in the same way, then I thought that that the soil from the cow enclosure would generate the most power because it contains cow manure and urine.  I hypothesized that it has more microbes that can be used to generate microbial power.  I also thought that it would provide the most consistent power.  

As the number of nutrients and types of microbes affect the ability of MFCs to make power, I tested a variety of soils from a variety of different places.  After obtaining approvals to collect soil samples, I built MFCs using the MudWatt system.  I also tested the soils using a soil nutrient test kit to see if there are dramatic differences that I can detect due to nitrogen, phosphorus, potash or the pH level.  I took measurements from each MFC generating power every day for 30 days.  The temperature of all MFCs will remain constant, and make sure the only variable tested is the soil type

I concluded that my hypothesis was incorrect. What happened was Frog Pond made the most power.  However, it was not the most consistent of all my samples.

  • Greatest Power Generated - Frog Pond (165 µW)
  • Least Power Generated - Stream (0 µW), Garden (3 µW)
  • Most Consistent Power - Forest (9 µW +/- 2 µW)
  • Most Inconsistent Power - Frog Pond and Cow Enclosure
  • Longest Lasting Power - Forest (28 days), Agriculture (28 days), and Decomposing Tree (27 days)
  • Shortest Power Generated - Garden (2 days), Frog Pond #1 (2 days), Frog Pond #2 (15 days), Cow Enclosure (17 days)
  • Generated Power Quickly - Frog Pond #1 (1 day), Forest (3 days), Frog Pond #2 (4 days)
  • Generated Power Slower - Garden (19 days) Cow Enclosure (14 days)

What interested you in an experiment using Microbial Fuel Cells?

A year or two ago, my dad funded a Kickstarter campaign for MudWatt.  He thought it would be cool for me and my brother to experiment with.  We dug up some soil from the Garden and in a week or so, we noticed that it started working.  That MudWatt just stopped blinking a few months ago. 

I was very interested, and I had more questions.

I wanted to know how microbes making power could benefit our communities, and maybe even help save the Earth as a source of alternative energy.  After my dad brought home that MudWatt I decided to shoot higher. I thought maybe we could stop or slow down global warming and climate change.

I wanted to know how much power microbes could generate and if it was sustainable for a long time. I even dreamed about using this technology to give a spaceship power so that we could go to Mars, and very recently scientists discovered a type of microbe(cyanobacteria) that can grow anywhere, and they were responsible for pumping oxygen into our atmosphere as Earth was forming!  It has been one of my personal lifelong dreams to discover if we can finally go to Mars or another planet and colonize there.

In the future, I want to try and find out if cyanobacterial is exoelectrogenic.  If it is, it will make colonizing another planet easier.  We could finally go to the planet, like Mars, and release cyanobacteria on Mars’ surface. Then we would wait for them to release oxygen into Mars’ atmosphere while we are waiting, we can send a rover.  We can use the technology that I am using for this experiment to power the rovers.  The rovers can test the oxygen levels and see if they are high enough for us to colonize there.

I realize that this will be harder than I thought since creating a biosphere on another planet that mimics Earth is very complicated.  Scientists learned in the Biosphere 2 project in the 1980s that they don’t know as much about the Earth systems as they thought and how to make the project bigger, so it can last on another planet.

What was the most surprising thing you learned during this experience?

There was a lot that surprised me.  The thing that surprised me most was that cow enclosure didn’t start blinking until day 13 of  the experiment.  I expected it to blink much faster than it did during the 30-day test.  I also expected it to make more power.

I was surprised that Stream didn’t ever blink.  I think that it is because the sample had so much rocks and not a lot of sand or what I think of as usual dirt.  Next time I think I need to take more from a dirtier part of the stream that has slower or standing pools of water.

I was surprised that Garden did not blink very long or very much because we did a test of some garden soil when my dad got the first MudWatt a long time ago.  We took this dirt from a different part of the garden though, where not a lot of plants grow.

Frog Pond generated the most power.  There was one day that I almost didn’t want to go to school because the power was climbing so quickly.

There are articles that say people are talking about not using phosphorus because it is bad for the environment.  With the exception of Frog Pond I found that that there may be more power made with higher phosphorus levels.

Research I found said that composted cattle manure increases microbial activity.  I think my data supports this.  As the cow enclosure composted in the MudWatt it started making more power.  Power was increasing quickly at the 30 day mark for the project.

Other research said worms increase microbial activity.  I saw worms in agriculture soil samples, frog pond, and forest.  I saw a lot of power from frog pond, but it was a burst.  Agriculture and forest have less power, but it is more consistent and keeps going.  I can’t draw a conclusion from this.

Other research said clay was the best for generating power.  My garden soil has a lot of clay, but I did not see much power.

If you could do your project all over again, is there anything you would change?

If I could do this experiment again, there are a few variables I would change, and a few new experiments based on what I learned.
I would like to
·          Determine the impact of temperature fluctuations on one type of soil.
·          Determine whether cyanobacteria are exoelectrogenic.  Cyanobacteria is theorized to be able to live in outer space.
·          Determine if soil samples from a slower moving part of a stream with less rocks will generate more power.
·          Submit highest performing soils to a lab to identify which microbes are present and in what quantity.
·          Make the size of the anode bigger to determine the impact of anode surface area on power generated
·          Combine a variety of the soils and record the results.  I found research that said mixed soils produced higher energy levels.

If you had to do a follow up project to this what do you think you would do?

If I could, I would want to test all the soil for what specific microbes are present and how many were present in the soil so I could compare the results.  I would really love to get some soil with cyanobacteria and see if it is exoelectrogenic.