Nature and diversity of life forms on Earth never cease to amaze me. I find it astonishing that certain microorganisms can get their energy by solubilizing iron based minerals, some can get their energy solely from the sun, while others thrive in the high pressures of deep seas. In Inno Indigo project Bio-e-MAT, we also focus on one extraordinary group of microorganisms: microbes that can generate electricity straight from waste materials in special bioreactors known as microbial fuel cells.
At first, the idea that microbes can produce electricity may seem bizarre, but it all starts to come together when looking at basic principles of electricity and microbial metabolism. Electrical current is, in essence, flow of electrical charges, whereas microorganisms obtain energy for growth through series of oxidation and reduction reactions, where electrons are transferred from one chemical compound to another. Therefore, it is actually quite natural that microorganisms can be coupled to electricity production.
In microbial fuel cells, microorganisms grow on anode by utilizing biodegradable components of a waste stream as source of energy and donate the electrons released in the metabolic reactions to the anode electrode. The electrons flow through an external circuit and a load to the cathode electrode, where the electrons react for example with oxygen and form water. Constant production of electrons at the anode and consumption of electrons at the cathode generate flow of electrical charges i.e. electrical current.
Microbial fuel cells enable simultaneous waste treatment and electricity production and provide hence a very interesting way to produce renewable energy. However, the high cost of construction materials and relatively low efficiency of electricity production in these systems has so far restricted their use in large scale. Optimization of these systems requires expert knowledge on many fields, including material science, electrochemistry, bioprocess technology, waste treatment, bioengineering, energy production and microbiology.
In Bio-e-MAT project we at Tampere University of Technology have joined forces with Yildiz Technical University (Turkey), CSIR-Indian Institute of Chemical Technology (India) and Indian Institute of Technology Delhi (India). Our aim is to develop a novel microbial fuel cell with low-cost and efficient electrode and separator materials that can be used for biological electricity generation from waste streams. At the same time we hope to learn more about these amazing “electric" microorganisms.
Text: Aino-Maija Lakaniemi