Fuel cells use bacteria to make energy from waste

[Source: Jeremy Shere, Earth & Sky Radio Series] - Rittmann's work can genereate energy from waste in polluted water. (Credit: David Villa. Some rights reserved.)

Bruce Rittmann: There’s a tremendous amount of biomass out there in the world that’s going untapped, a huge renewable energy resource.

That’s Bruce Rittmann with the Biodesign Institute at Arizona State University. He and his colleagues are working on using bacteria to produce energy from the organic waste materials all around us.

Bruce Rittmann: Now we can get electrons out of organic material, put those electrons into the anode of a fuel cell and then the rest of the fuel cell works. So we get combustion-less, pollution-free electricity.

Rittmann said that as this technology develops, microbial fuel cells could tap into a vast source of renewable energy.

Bruce Rittmann: There’s a very large amount of biomass out there. If you look at it worldwide, if we could collect all the residual biomass waste materials —unused agricultural materials, things like that — capture them and convert them to electricity this way, we could meet something like 25% of the world’s current energy demand.

He said microbial fuel cells are in an early stage of development. But these scientists believe this technology will one day help decrease our dependence on fossil fuels.

Bruce Rittmann: So if we can get microbial fuel cells to work we can generate out society’s most valuable energy source, electricity, from renewable sources and without pollution, so it’s really the ideal way to go.

Rittmann explained that, in working with the development of any fuel cell, researchers are trying to take something that is, as he says, ‘rich in energy and electrons.’ The researchers try to extract the energy and electrons out without creating combustion.

A microbial fuel cell is a special class of fuel cell. It contains a biological film called a ‘biofilm’ that actually lives within the fuel cell.

Bacteria in the biofilms within fuel cells are useful because they have the ability to metabolize organic material. Some of them can actually transfer electrons to the anode of a fuel cell. The organisms that can do that are the key to the success of this technology.

Microbial fuel cells are capable of removing electrons from a large range of organic materials. ‘That’s what microorganisms do to do live,’ said Rittmann. Some of bacteria are capable of transferring electrons to an anode of a fuel cell, so that you get combustion-less, pollution-free electricity.

Furthermore, the organic material can come from biomass, giving humanity an alternative to petroleum and other nonrenewable energy sources.