Not wasting wastes: Microbes are our allies
We’ve all known for a while now that it is possible to generate electricity by exploiting the microbial ecosystem, and recent developments from researchers at Stanford University prove that this alternative fuel source is becoming more and more viable–to the point where its efficiency can match that of solar power.
Sewage wastes and other organic ‘pollutants’ are often considered hazardous to most living things on earth, but to a handful of microbes this sludgy and oxygen-depleted environment is an Eden where they can thrive. As these exoelectrogenic microbes—organisms that are capable of surviving in ‘airless’ environments and possess the ability to react with oxide materials to ‘breathe’—eat up our waste materials, they generate a decent amount of extra electricity that we can harness to perhaps power our own life-enhancing contraptions.
The researchers’ lab currently sits in a D-cell-sized bottle where the microbe’s excess production of electrons is being fished using two electrodes. In the past several years, scientists have tackled the matter of capturing useful energy from microbes with little success as efficiency continued to hamper further development.
The latest development, however, has revealed that it is possible to draw energy from exoelectrogenic microbes using a simple and efficient design.
A single filament the width of a human hair can accommodate about 100 of these microbes, and as they ingest the organic waste matters they generate excess electrons which flow across the silver oxide filament. The silver oxide then gradually gets reduced to silver, and by the end of the day enough electrons are absorbed that the silver can be removed and get re-oxidized back into silver oxide and the stored electrons is released.
According to researchers, their microbial battery can extract about 30 percent of the potential energy in waste water, which is about the same amount as the best commercially available solar cells.
The promising development does have its drawback as the use of silver on an industrial scale is extremely costly. However, the researchers are hoping that in the near future they can find a cheaper alternative to silver, so that we don’t waste the wastes.
“We demonstrated the principle using silver oxide, but silver is too expensive for use at large scale,” said Yi Cui, a material scientists and associate professor at Stanford. “Though the research is underway for a more practical material, finding a substitute will take time.”