Mud power: how bacteria can turn waste into electricity

Microbial fuel cells: a bit of mud or sewage, a few bacteria and, bingo: electricity. engineering for change

When you read the word “bacteria” you probably think about illness, advertisements for “probiotic” food supplements, and maybe about brushing your teeth.

Chances are, you probably don’t think about electricity.

As it turns out, bacteria can be used as a source of electricity, and recent research has produced some surprising findings.

It seems that bacteria have been plugged into each other all along and this finding could open entirely new opportunities in bioenergy production.

Breathing metal

Derek Lovley, a Distinguished Professor at the University of Massachusetts Amherst and the head of the Geobacter project, found that some bacteria naturally produce electricity through their ability to “breathe” solid lumps of iron in the soil.

We can harvest this electricity from the bacteria using devices known as microbial fuel cells (MFCs).

An MFC is made up of two electrodes – an anode and a cathode – linked by an electrical connection. Bacteria breathe out electrons, produced as part of their normal metabolism, onto the anode. These electrons can be collected as an electrical current.

The electrons are then passed to the cathode to complete the electrical circuit and create a kind of battery.

Bacteria capable of producing electricity occur naturally in almost any type of mud, sewage or waste. The bacteria usually use this process to breath without oxygen.

Turning this natural process into a functioning MFC is as simple as filling the MFC with mud, sewage or waste and waiting for the bacteria to grow.

Bacterial batteries

The bacteria that can produce electricity do so by directly transferring electrons to the anode. They do not use any intermediates or shuttles; in effect, they reach out and touch the anode.

How an MFC works MFCGuy2010