The soil under your feet hosts the world’s next clean, sustainable source of energy. Geobacter sp. and Shewanella sp., soil bacteria, “poop” electricity. Actually, their “waste products” are electrons, hydrogen, and carbon dioxide that can be captured in a Microbial Fuel Cell turning microbial “poop” into electricity.

Capture the Waste!

Microbial Fuel Cell
Diagram of a soil based Microbial Fuel Cell by MFCGuy2010. Used under CC BY-SA 3.0.
When any organisms breaks down food, it releases the energy stored in that food in the form of electrons. With most organisms, from mammals to microbes, the electron “waste” binds to oxygen, iron, or sulfur inside the cell(s) of the organism to conduct other processes. Electrogenic bacteria give off their electrons into the soil around them. An MFC captures those lost electrons using electrodes and wire to complete a circuit and generates electrical current. The energy harnessed can then light up a LED, run a clock, thermometer, or any of a number of other things.

Electrogenic bacteria can be found naturally in soils all over the world. If the soil is stinky, you’ve found Shewanella and Geobacter having a party. In addition to giving off electron “waste” these electrogenic bacteria release stinky sulfur compounds. Think of the rotten-egg smell of mud in a swamp or marsh. I found a pot of daffodil bulbs that didn’t drain properly and started to rot. The stink immediately made me think of healthy populations of Shewanella and Geobacter. That stinky soil will get our MudWatt MFC working quickly this weekend.

MudWatt – A DIY Microbial Fuel Cell

Want to do your own MFC experiments? The MudWatt is a fantastic STEM education kit has everything you need to make your own MFC using whatever soil and experimental conditions you choose.  The basic kit includes electrodes, a chamber with lid, membrane, led light, and other necessary equipment. You decide what soil to use, what “special ingredients” to add, and other conditions such as temperature.

The MudWatt kit and the subsequent business Magical Microbes was inspired and developed by Keegan Cooke from the educational outreach work he did. In 2010, he was a scientist in a private company working on developing MFCs at the ocean bottom for military use. Seeing kids eyes light up and fielding their many questions when he took “buckets of dirt that lit lights” out to educational events, Keegan knew there was a need for this science kit. He teamed up with an engineering friend, Kevin Rand and they started tinkering. Karen Manning rounds out the team as the educational specialist. Karen’s accompanying educational materials are OUTSTANDING!

Contents of the MudWatt Science Fair pack the kids and I tested from Magical Microbes.

Tested and Retested

Magical Microbes sent us a Science Fair kit that my kids, playdates, and fellow moms have experimented with. Do the MudWatt bacteria grow faster with granular or powdered sugar? White or brown rice? Compost or soil from the yard? A friend borrowed the kit for an elementary school STEM night and set up yard soil versus commercial topsoil. I’m looking forward to using them time and time again for demos in my General Microbiology course, outreach with preK-12 students, STEM club/STEM nights, and Girl Scouts. I’ve also purchased the Science Fair kit for my nieces to experiment with this summer and need to get more for outreach and scouts!

Jac preparing our first MudWatt experiment.
Jac’s MudWatt sugar experiment.


A mom-friend demonstrating the MudWatt and talking about Microbial Fuel Cells at an elementary STEM night.


Girl Scouts “GET MOVING” with MudWatt

Jac’s new Junior Girl Scout troop is doing the “GET MOVING” journey this fall to study different types of energy and energy conservation. For a few meetings, the girl’s will set up MudWatt experiments to optimize their energy production! I can’t wait to see what soils they decide to use and/or ingredients to add. What conditions will produce the most energy? What other findings might they make? Stay tuned for how that goes. Similar to the GET MOVING journey, Keegan’s goals with MudWatt, DoughLab, and future Magical Microbes kits is to excite kids about the fun and creativity in science and engineering, while connecting to their local environment.

We want kids to see that science and engineering is fun, and inherently creative.  We want them to see that there is still magic in the world (right beneath their feet) which can be explored through science and engineering.  And we want them to develop an empathy for the environment and show them that the environment (even dirt) is a living system that must be taken care of. – Keegan Cooke, CEO and founder of Magical Microbes

Keegan related one example of Ricky, a kid in California, who using soil from his local river in his MudWatt, produced twice as much power as the Magical Microbes Team had ever produced in their lab! Ricky and his dad found out a waste-water treatment plant upstream might have released additional nutrients into the river. That’s neat since MFC’s are being investigated for cleaning waste water! Exciting to see a kid independently discover this use for MFCs. Wouldn’t it be interesting if one day your backyard septic tank powered a microbial fuel cell? Your household waste could be cleaned up AND produce power! Even better, big businesses such as agriculture and food and beverage processing could use this method to take their human waste to make microbial waste to then make human treasure – hehehe. The power of microbes – their poop and farts are our food and energy!

If you’re excited about the “treasures” that we humans get from microbial “trash”, check out Magical Microbes Kickstarter Gold campaign until August 1,  2017. You can purchase individual and classroom/outreach sized kits of the MudWatt and DoughLab together or separately. GiantMicrobes stuffies of yeast and Geobacter are included for microbial snuggling fun! They are so darn cute, I’m tempted to award the team that produces the most electricity or a GeoBacter stuffy from Giant Microbes.

Other related posts:

Microbial Trash is Human Treasure, Part I: Food – Fungal Farts and Bacterial Poop

GiantMicrobes: When Teachers Throw Things

Farty party and Brains On! excellent Farts podcast

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