Published on September 17th, 2013 | by No Artificial0
Electricity From Sewage
Stanford scientists have developed a method using microbes to generate electricity from sewage and wastewater.
The team at Stanford University unveiled a new way to generate electricity from sewage using naturally-occurring microbes as a power plants, producing electricity as they process plant and animal waste.
In an article published in the Proceedings of the National Academy of Sciences, co-authors Yi Cui, an associate professor of materials science and engineering, Craig Criddle, an environmental engineer, and Xing Xie, an interdisciplinary fellow, have named their invention a microbial battery.
According to Stanford researchers, the system can extract about 30 percent of the potential energy locked in wastewater and it is as efficient as the best commercially available solar cells convert sunlight into electricity.
The new technology relies on naturally occurring microorganisms that feast on plant and animal waste for their own biological fuel.
In the prototype design the feasting microbes attach themselves onto carbon filaments.
Their excreted electrons flow from the filaments to a positive electrode made of silver oxide, a material that attracts electrons. They gradually reduce the silver oxide to silver, storing the spare electrons in the process. At that point the electrode is removed from the battery and re-oxidized back to silver oxide, releasing the stored electrons.
The engineers say their biggest obstacle will be finding a cheap but efficient material for the positive electrode.
“We demonstrated the principle using silver oxide, but silver is too expensive for use at large scale,” explained Yi Cui.
“Though the search is underway for a more practical material, finding a substitute will take time”, he added.
Once an alternative material is found, the scientists hope to scale up the technology for commercial production.