Blog > Making of Mud Cells>

>”What if gardening can be an act of producing electricity?”

1. The wetland map of Eindhoven for collecting mud samples.
2. Idea of a garden as a power plant. 

⛰︎Here, we will take you through the mud cell making experiments we have done so far. Artist Sunjoo Lee is leading the thread of Microbial Fuel Cells and Earth Battery makings.

⛰︎Once Sunjoo Lee dreamed of a tree and a computer all merged together, forming one body and functioning as one body. In her imagination, the tree’s roots were all tangled up with the inner part of the computer, behind the screen, where the tree’s veins would be feeding the computer with energy. After a few years, Sunjoo found a nice way to make a real-life functioning hybrid of electronics and nature, which are the mud-based power cells. 

⛰︎The mud generates small amount of electricity, and an energy harvesting circuit can save this small current into a capacitor or a battery. After about a few hours to few days, the amount of energy builds up to a sufficient amount, to make an electronic device such as an arduino run for a short amount of time.

⛰︎ There are two ways of making electricity with mud and electrodes - The earth battery and the microbial fuel cell. The microbial fuel cell is what the team of Tree-001 is the most busy with. The microbial fuel cell harnesses the anaerobic respiration of bacteria living in the mud to gain electrons. The more food there is in the mud for the bacteria, and the more diverse species of anaerobic bacteria are there in the mud, the more power it produces.

⛰︎We learn everything ourselves by looking up the knowledge from websites, videos and and scientific papers, and modifying the methods to what we can achieve in our atelier, and we try them out.

✿Also look into the workshops we did!


one example of how microbial fuel cells work

〰This is the diagram of how the microbial fuel cell works. It uses two of the same material of electrodes unlike earth battery. The cathode and anode are both conductive, porous materials. We use carbon felt or activated carbon for this.

〰The Bacteria which is the green big oval in the diagram, is doing an anaerobic respiration, taking in organic substrate and giving out Hydrogen ion, CO2 and electrons. The bacteria needs to be happily living on the anode, so it is important to make the anode a good home for the little collaborators to make biofilm on.

☀︎Before we understood exactly how to make microbial fuel cells, we were mostly making earth batteries, which uses the chemical reaction between the zinc and the wet soil to produce electrons. This needs two different types of metal as electrodes. 

☀︎The image is the earth battery we made the first time. We could harvest the energy coming from the cells and charge a small lipo battery over a few days.

𓇼As we started to understand more the working principles of the microbial fuel cells, Sunjoo went around the city of Eindhoven to collect mud from wetlands, from the bottom of the water, in search of the right microorganisms

𓇼With the help of many students of Design Academy Eindhoven, Sunjoo collected different samples from different spots of Eindhoven.
⚡︎The different spots of wetlands had different kinds of mud. Some sandy, some more muddy, some silky, some more smelly than others... Some had greyish color, some very dark as black, and the most had the muddy brown color.

ᨒHere are some photos of Sunjoo’s personal Microbial Fuel Cell experiments. And the first big batch created with students.

ᨒIt was a success. The different mud from different places started to create different amount of voltage and current over time. Usually with the microbial fuel cells, it takes at least a few days for the electricity to be generated, and the more you wait, the more the amount of energy climbs up, as the bacteria settles into the bottom of the mud at the anode more and more.

ᨒAfter about two weeks, the most powerful mud jars each produce about 0.75V and 1.2mA. Mud from the river Gender and Dommel at the South of Eindhoven produce the most electricity.

ᨒ Graphs of Voltage and Current measurements from day 1 to 145.

︎The mud cell experiments were exhibited at Stimuleringsfonds exhibition during Dutch Design Week 2024.

𖡼 This is a microbial fuel cell about 2 weeks old. At the time of measuring with the scope, the cell was giving off 0.25V and 0.20mA of electricity.